You are going ot have to make application to probate
her will here.You will be seeking to be named personal representative(executor).The court has to admit the will into probate and appoint you and give you letters testamentary.Once you have the letters you have the right to sell the property and sing the deed and other closing documents.
You woudl be expected to gather assets, pay claims, and any taxes the deceased owed as part of probate.You are going to need a local probate lawyer to help you make application here.This is going to delay the sale a bit probate from start to finish takes about a year.But you will need to have your letters testamentary here and an inventory filed prior to any sale of property.Once you have done these tow things you have right to enter into listing agreement, sales contract, and closing documents as personal representative(executor).
Being named on the death certificate I am afraid does not mean the will has been probated and you appointed the personal representative.This has to be done prior to any listing and sale of property to give you legal authority to sell it.
There would not be federal estate taxes due here but ther may well be PA state taxes.Here is information on those.
Additionally the deceased may have a last federal income tax due if this was not done in the year she deceased and there was income.
You may want to go over these issues with the probate lawyer and a tax preparer..
Here is lawyer referral.http://www.pabar.org/public/membership/lrsblurb.asp
More information about probate in PA.Here you would fine in the county where she deceased.http://www.nolo.com/legal-encyclopedia/pennsylvania-probate-an-overview.html
I do appreciate the chance to help you today.It has been my pleasure to do so.I know all of this can be kind of overwhelming.Please let me know if you have more follow up.Thanks again.