It’s established she is a meanie. Rude. Terrible.

At this point disengaging is the only way. You can fight with your husband about it or tell her off but that won’t change much of anything. He can’t change his mother. He told her off and now she made her comments more subtle. She didn’t change who she is but she is smart, her critique just being more sneaky. All we can change is what we do.

Since complete estrangement is not favorable in this situation, limit the contact. You don’t need to announce it to him. Just limit it. You went out with her twice two nights in a row. I don’t go out two nights in a row with people I like! For sure not with people I don’t like. If she only visited for two days, I’d maybe go two days but she is here for a long time and it’s unreasonable to eat with her daily. Your husband could if he wants to. There is zero reason for you to do so.

As in most situations we cannot change other people (unless these are kids or younger people who still need educating). We change ourselves and our actions