Hi Cindy - just finished reading through this thread - and all the great advice coming from cat lovers. D'you know what I was wondering - could your Mum's cat be bored ? If he's down in the basement all the time he has nothing to watch. If he came upstairs he could look through the windows - he might be more entertained. And he'd have more contact with your Mum - maybe he's lonely too.
Hope all goes well

Lynne