technically....
on the 1st stimulus payment, the law was 'flaky' and the IRS finally ruled that if the person died prior to receiving the payment they were to return it to the IRS. I don't believe there is any 'teeth' in this but the IRS was looking to the goodwill of the public and folks to 'do the right thing'.
well, that fired up Congress, so when they passed the 2nd stimulus, they made the law very, very clear. anyone living on Dec 31, 2019 who met all the other rules of stimulus eligibility remained eligible to receive the stimulus.
So technically, if you spouse passed in Feb, 2020 and your received the 1st stimulus, it should be returned.
for the 2nd stimulus, it is quite clear, you keep it.
here is just one article that discusses this confusion.
https://www.aarp.org/money/taxes/info-2020/stimulus-check-in-deceased-name.html