Definitely an unsatisfactory choice of round holes into which to pound this square peg.  But maybe this is why God (or IRS) gave us Form 4852.  Since the 1041 is already late, why not try reporting the income and withholding that way.  Run it up the flagpole and if no one salutes, fall back to the 1041.  At least the income will be reported in the correct year for the widow.

How much was paid in wages, and how much was withheld for FICA taxes?  The widow should ask the employer for a refund of those.  (Should have done that long ago.)  

Direct deposits and automatic withdrawals are wonderful until someone dies.