Terminating plan with unresponsive beneficiary

[PS]

Hi, 

We received a DC 401k plan for termination in 2020, since they had filed for 5310 the termination was on HOLD.  In 2022 they received a determination letter and was good to start the termination.  The plan has 32 deceased participants the Plan termination notice was sent to the deceased address as well there was no response and since the named beneficiary did not respond with the sponsor's direction the check was cut to the estate.  There was a tax deduction on $90,000 the check was cut in September 2023 and the spouse received the check and responded in Feb 2024.  I'm looking for some guidance how the tax record can be corrected?  also is there a 5 years payoff rule for deceased account?