When the return is processed, chances are that the IRS will lock the account because it has received a return filed by a deceased person. (The deceased spouse was the filer of the return instead of the surviving spouse.)

If the IRS processing went as they should, Notice CP01H would be sent to the filing address.  Follow this link to fix the problem.

   https://www.irs.gov/individuals/understanding-your-cp01h-notice

If the IRS processing didn't go as they should, improvise. 

I'd side with @George4Tacks. Filing an amended return at this point could mess it up more because by the time the amended return is processed (it would just be the 2,000,001st item to be processed from this point), the account could well be locked.

Not a bad idea to give the Tax Practitioner Hotline a try.