What’s the best way to stop an old couple from coming to my front door?

Let me elaborate. My mom is concerned about an elderly couple that lives in my neighborhood. They’re quite upset she says. She’s concerned that they’re going to die in their house and nobody will even know. She cares about them and wants to make sure they’re doing well. She even goes to their house to ask how they’re doing. But I’m upset over this. I think it’s a breach of privacy and I don’t want them coming to my front door. Is there a way I can block them from coming to my front door without being rude? I’m also concerned over the fact that my mom could be concerned for the wrong reasons.