Let me express my sympathies on the loss of your mother. You should have an easy time of administering this estate. It is considered a "small estate" for probate purposes and requires very little be done. I am going to give you an excerpt from the Code which tells what you have to do. Also, I am going to give you a link to a website providing the necessary forms. I have no financial interest in these forms, and you may be able to obtain these free at the courthouse or elsewhere. But this will show you what you might need.
18-A M.R.S.A. § 3-1201. Collection of personal property by affidavit
(a) Thirty days after the death of a decedent, any person indebted to the decedent or having possession of tangible personal property or an instrument evidencing a debt, obligation, stock or chose in action belonging to the decedent shall make payment of the indebtedness or deliver the tangible personal property or an instrument evidencing a debt, obligation, stock or chose in action to a person claiming to be the successor of the decedent upon being presented an affidavit made by or on behalf of the successor stating that:
(1) The value of the entire estate, wherever located, less liens and encumbrances, does not exceed $20,000;
(2) Thirty days have elapsed since the death of the decedent;
(3) No application or petition for the appointment of a personal representative is pending or has been granted in any jurisdiction; and
(4) The claiming successor is entitled to payment or delivery of the property.
(b) A transfer agent of any security shall change the registered ownership on the books of a corporation from the decedent to the successor or successors upon the presentation of an affidavit as provided in subsection (a).
18-A M.R.S.A. § 3-1202. Effect of affidavit
The person paying, delivering, transferring, or issuing personal property or the evidence thereof pursuant to affidavit is discharged and released to the same extent as if he dealt with a personal representative of the decedent. He is not required to see to the application of the personal property or evidence thereof or to inquire into the truth of any statement in the affidavit. If any person to whom an affidavit is delivered refuses to pay, deliver, transfer, or issue any personal property or evidence thereof, it may be recovered or its payment, delivery, transfer, or issuance compelled upon proof of their right in a proceeding brought for the purpose by or on behalf of the persons entitled thereto. Any person to whom payment, delivery, transfer or issuance is made is answerable and accountable therefor to any personal representative of the estate or to any other person having a superior right.
18-A M.R.S.A. § 3-1203. Small estates; summary administrative procedure
If it appears from the inventory and appraisal that the value of the entire estate, less liens and encumbrances, does not exceed homestead allowance, exempt property, family allowance, costs and expenses of administration, reasonable funeral expenses, and reasonable and necessary medical and hospital expenses of the last illness of the decedent, the personal representative, without giving notice to creditors, may immediately disburse and distribute the estate to the persons entitled thereto and file a closing statement as provided in section 3-1204.
18-A M.R.S.A. § 3-1204. Small estates; closing by sworn statement of personal representative
(a) Unless prohibited by order of the court and except for estates being administered by supervised personal representatives, a personal representative may close an estate administered under the summary procedures of section 3-1203 by filing with the court, at any time after disbursement and distribution of the estate, a verified statement stating that:
(1) To the best knowledge of the personal representative, the value of the entire estate, less liens and encumbrances, did not exceed homestead allowance, exempt property, family allowance, costs and expenses of administration, reasonable funeral expenses, and reasonable, necessary medical and hospital expenses of the last illness of the decedent;
(2) The personal representative has fully administered the estate by disbursing and distributing it to the persons entitled thereto; and
(3) The personal representative has sent a copy of the closing statement to all distributees of the estate and to all creditors or other claimants of whom he is aware whose claims are neither paid nor barred and has furnished a full account in writing of his administration to the distributees whose interests are affected.
(b) If no actions or proceedings involving the personal representative are pending in the court one year after the closing statement is filed, the appointment of the personal representative terminates.
(c) A closing statement filed under this section has the same effect as one filed under section 3-1003.
18-A M.R.S.A. § 3-1205. Social security payments
If, (1) not less than 30 days after the death of a Maine resident entitled, at the time of his death, to a monthly benefit or benefits under Title II of the Social Security Act, all or part of the amount of such benefit or benefits not in excess of $1,000 is paid by the United States to the surviving spouse, one or more of the deceased's children, or descendants of his deceased children, the deceased's father or mother, or the deceased's brother or sister, preference being given in the order named if more than one request for payment shall have been made by or for such individuals, upon an affidavit made and filed with the Department of Health, Education and Welfare by the surviving spouse or other relative by whom or on whose behalf request for payment is made, and (2) the affidavit shows the date of death of the deceased, the relationship of the affiant to the deceased, that no personal representative for the deceased has been appointed and qualified, and that, to the affiant's knowledge, there exists at the time of filing of the affidavit, no relative of a closer degree of kindred to the deceased than the affiant, then such payment pursuant to the affidavit shall be deemed to be a payment to the legal representative of the decedent and, regardless of the truth or falsity of the statements made therein, shall constitute a full discharge and release of the United States from any further claim for such payment to the same extent as if such payment had been made to the personal representative of the decedent's estate.
Here is a link to a website with forms for sale:
Of course, you can always consult with an attorney in Maine. But, since your mother had so few assets, it does not seem necessary. The courthouse personnel are often very helpful and may be able to do a lot of the work for you.