Who decided on a fiscal year and when was the decision made?  Smart thing to have done earlier this year is file with a fiscal year ending January 31.  Too late to make that election now.  But you can still file a late calendar-year return, probably showing little or no income through 12/31; maybe losing some of the deductions if administrative expenses were paid right away.  You might not even have a filing requirement, if there was no income from 11/22 to 12/31, although I sense there were some mutual funds with CGD's.  (Maybe not enough to get out of the 0% tax bracket.)  

How is it going to be a final 1041 if the estate hasn't been closed because the tax returns haven't been filed?

You don't use 1099's for a fiscal-year return anyway, you use monthly statements and trust accounting ledger.  So you could prepare and file the return by mid-November, beating the tax-season rush.  Collect your fees by October so they'll be deductible.  Maybe it can be a final return if the rest of the estate closing requirements are done.