My father-in-law just passed, do we need to close their joint bank accounts and open one for his wife?

Check with the bank. It used to matter if the checks said "and" so and so, or "or" so and so. I don't think that matters anymore. When my dad died, I never had to change a thing on Mom's account, but you need to call the bank and ask them what their rules are.
Take care,
Carol

Hi Carol, I checked with the bank and they said no but our financial advisor recommended it because of possible fraud that is perpetrated.

There are people who steal the identity of the dead. I don't know how easy that is to do now but it has been done in the past. In fact, my now deceased MIL was agressivley courted by a man who had done this in the past. We were able to get her to see him for what he was but he was a lifelong criminal. Can't be too careful.