I am very sorry for your loss.
Note the following:
Name of Decedent
If you are filing a joint return for spouses who are both deceased and you are required to file Form 1310, you must do the following.
• Complete a separate Form 1310 for each spouse.
• Attach both of these completed Forms 1310 to the return.
See https://www.irs.gov/pub/irs-pdf/f1310.pdf
