P.W.
I do not have a mom like this, but I have another person in my life like this. Here are a few things that helped me.
1) Protect yourself. If you can avoid staying with your mother (one of you in a hotel) then do that. If this is not possible then set up other ways to give yourself a break. Schedule things in before you end up together. For example, if you are going to her house and know someone in town. Set up a lunch.....hopefully away from your mother. However if you feel you must invite your mother then warn your friend and let her know you just need her there. In that way if your mom acts up it won't be as embarrassing and you can better ignore or not react to her behavior. Just having another person in the mix helps. Same if she comes to you. Be sure to have a couple of appointments or lunches to free you from her and/or a routine with her.
2)Know your Mom is unlikely to change, so toughen up and do your best to slough off her behaviors while you are together. Listening to your mom, and smiling, is not necessarily agreeing with her. It will help with peace however. Don't get combative. What's the point?
3)Keep reminding yourself it's 2 days.
4)If your Mom is like my family member and can actually go a little nutty, screaming and the whole works.......Don't engage! Walk away. Have an exit plan. You don't have to put up with that. Fighting with her won't be productive. Remove yourself from the situation. So have a plan.
5)If your Mom is self-centered and must do things her way. Either do it her way for two days, or when she starts........laugh it off and just do it your way.
6)If possible, don't go alone. Be sure a spouse or friend is around as often as possible.