Sorry - for your loss.
Social security income - if that was only your father's income is not taxable.
You do not have to file a tax return for him.
Because his estate is only $8 - there is no requirements to file an estate tax return either.
However even you do not have to file - you might want to file a final return for your father - but you are not required.
For trust - you need to file a trust income tax return - form 1041 - http://www.irs.gov/pub/irs-pdf/f1041.pdf
Filing requirements are based on
Gross income for the tax year of $600 or more - see instructions page 4 - http://www.irs.ustreas.gov/pub/irs-pdf/i1041.pdf
If the trust sold the house - I assume that gross income is more than $600 - so you need to file tax return even there is no any taxable income and you do not owe any tax.
Let me know if you need any help.
Tax Preparer
Taxes, Immigration, Labor Relations