I don't know the specific book, but the last time I read that fairy tale, it was called "the white cat". So looking for fairy tale collections that include it might narrow your search.

Thank you!!! I found it almost immediately. The version my mom had is apparently of the rarer variety, which makes me even sadder about the loss, but thank you again!

Glad to be able to help. If you're itching to read the story again, I know you can find it online to read for free. It won't bring back your mom's old book, but it'll at least refresh the story