Cats scratching walls after using litter box, causing damage. How to fix?

Listen, I know scratching the walls after using the litter box or eat is normal cat behavior. my 11 year old lady has done it after pooping all her life. My new cat (6 years, male) does it too.

However, it's causing damage to the wall where they do it. We moved into a new place that my mom owns and one of the litter boxes is in the bathroom. That's the one where the wall damage occurs. It's never caused damage with the other cats before, and for some reason my mom is determined to blame my boy that I got a couple months ago for it. She says both cats have to stop or she's going to kick them out. I can't afford to move.

How do I get them to stop scratching the walls without hurting them?