If a deceased client received income a year after their death, it sounds like no one reported to the payers that they were deceased.   If there is an estate, some one will have to notify the companies to switch the income to the estate's FIN  for that time period.

Estate Form 1041.

"SSA income,"

You can't collect Social Security when you are dead. That would need to be returned. Someone was supposed to be in contact with all the paying entities and make sure SS documents that SS# as deceased, to help prevent fraud.