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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.