It isn't you, it's her. She is feeling down as a mother so she feels better about herself as a mom by micro managing her child's daycare experience through you. (insert big sigh) I have a mom like this too. I always feel scrutinized with a sense of disapproval from this woman even though she has been with me for few years and I care for child #2. I think her guilt as a working mom plays a factor as well as the "no one does it better than me" attitude. Fortunately, she doesn't do a lot of the pick ups and drop offs.
I would address with her the last minute changes in diet. I would tell her that you do have your meals planed for the day and if she wants to eliminate a certain food group then perhaps she can provide that meal that day. I would just let the other requests like be careful about wiping her face due to chapped skin with a cheerful "thanks for letting me know" I think she will soon realize some of her concerns are baseless.
These people are really frustrating, but they don't really care how you take their comments or requests. They just do this to make themselves feel better.
Anyway, as for her questioning about your meal plans for the day. I would suggest you post a sheet up with what you have served. I do a daily sheet with my menu just so I don't get the questions at the end of the day. I am not a fan of any contact after hours unless it pertains to some sort of distress on the child's part that may have stemmed from daycare.