Okay, I think this is pretty harsh. This is her MOTHER. She is an adult, she just has her own topics that she finds interesting, or might spark conversation. Kick her mom out from Thanksgiving dinner, seriously? You'd be okay with one of your kids doing this to you?
I think warning others (if they've been there before, they know how mom is), is a good idea. Or, even before people get there, ask mom to try and keep conversation light and upbeat, as she (the OP) remembers how hurt she was last year, the hurt can be avoided etc.
I think short of causing family drama by just not inviting her, there are things that can be done. However, if mom has pretty much always been like this, even not inviting her won't make her change and just cause more hurt.