Can the wife of an ex felon own a gun?

Answer 1

That depends on the use of "ex-felon". If the husband was a convicted felon whose conviction was later overturned and their sentence reversed, then the husband is no longer a felon - that is an ex-felon. If the husband is a convicted felon who simply completed his sentence, that is not an ex-felon - that is a felon.
In either case, the wife retains the right to own a firearm. However, doing so in the case of a felon husband may send her husband right back to prison - under federal law, a felon may not purchase, possess, or be given access to firearms. Having a firearm in the same home can be considered allowing a felon access to firearms, even if kept in a gun safe.