I have a similar problem with my MIL but I don't "pander" to it. My MIL is not allergic to anything, she is not vegetarian or opposed to any foods for moral reasons, and she has no dietary restrictions due to religion. She is simply a 55-year-old picky eater who refuses to grow up and I can't stand it! DH and I have discussed this at length. Actually, she is not his mother, but his stepmother, for the record. Anyway, she has done this her whole life, made scenes in restaurants and this part of her "personality" is just the tip of the iceberg. For all of these reasons, I refuse to participate in this behavior and do not go out of my way to cook anything special for her.
Luckily, they live a few states away and only come to visit once per year, but it's usually at Easter. In years past, DH has given them a call about a week ahead of the visit to discuss "menus". She has gone as far as to try and dictate everything we should serve. I prefer ham at Easter, but she won't eat it, so since there were only four of us to feed, DH said to them, "We will cook a turkey breast." And she immediately said, "Why not a whole turkey? I like the dark meat."
Sorry, but when you dine in someone else's home, you eat what they serve! There are a few things I don't care for, such as mushrooms, and if they are in something I quietly pick them out and don't say a word. The first year they visited, she brought a cooler of "her" food and proceeded to fill up my already tiny refrigerator with it and then cook her own food in my kitchen. She thinks this is a good way to handle her "situation" but I think it's rude.
Anyway, if this was my own mother, I'd have a talk with her about it and see what kind of compromise could be worked out. Maybe start with "Mom, I noticed you do not eat many things, and at family dinners I need to know...." I wanted to try that with MIL but DH assures me that over the years, others have tried, and it always goes badly. But maybe with OP's mother she could be made to see that her daughter was trying to help without being totally inconvenienced and the mother would offer some suggestions and also offer to go without certain dishes to make things easier.