In the link in the comment from HelenC12:
Considering your xxx passed away in 20xx,... Therefore, there is not a return to add the income unless there was an estate opened. If there was no estate or probate opened or the estate was closed, then there is nothing you can add it to. If you want to be cautious you can put "deceased " on it and send to the IRS with a letter or you can address it later if they contact you over it.
