Just as long as the taxes are paid in full I see no reason why you would have to amend the tax return.  However, you may hear back from the IRS depending on how the deceased person's signature was affixed to the return. The IRS would like the word "Deceased" along with the date of death placed above the person's name on the return so that it is apparent why someone else is signing the return for that person. 

I do suggest that you contact the social security administration, (SSA) and notify them that the person has passed on. The SSA number is in the LINK below.

http://www.oprm.va.gov/docs/DeathNotificationChecklist.pdf