It sounds like you're in a tough situation, and you're getting a lot of great advice here. I agree with those who suggest being proactive--food and its scheduling is an issue you now know about, so initiating discussions about meals in advance is a great idea. Let's say that you suspect another one will be chores, like cleaning. Instead of tensing up and gritting your teeth and dreading the moment when your mom starts a PA discussion about vacuuming (if you're doing that), take the bull by the horns and bring it up with her yourself. Again she's probably worried about how the cleaning is going to get done if she can't stand for long, and there's three extra people plus a dog running around.
So maybe say, "Mom, I've been thinking about how we're going to divvy up the household chores. Here are some of the tasks I've thought of. Are there others you want done, and how often? Now obviously you can't do the vacuuming, so I'll be doing that, but probably only once a week, most likely Saturday afternoons. If I put the laundry in the washer and dryer, would you be able to sit on the couch and fold it? Could you sit on a chair in the kitchen and dry dishes I've washed after supper?" Only, you know, in a more natural tone...
I think one way to counter PAness is with clear communication. Lay out your plans for her, ask your questions in advance, and that way she doesn't have as much wiggle room to be PA, and you can point out to her when she's doing what irritates you. "Mom, I told you last night I'd be walking the dog first thing and wouldn't start cooking breakfast until 7am. So if you're hungry, you need to eat one of those granola bars or something, because I'm going to follow the plans I told you about earlier." Or, "Mom, I told you I'm going to pay that bill on the 15th, after my check comes. Please don't bring it up again." Of course, then you have a responsibility to follow through on the stuff you've said you would do, because you're trying to train her to trust your word instead of making little PA comments.
