This is clearly dcm's issue and insecurities coming out.
Honestly, don't take her nonsense personally. I agree with Mimi, when she says something that makes you feel second guessed have a standard reply "Thanks for letting me know" is a really good one! I usually give a "mmmhmm" and smile and nod and the moment I shut the door I know that its MY rules.
As for the menu thing. I have tried a weekly menu and I am like you fly by the seat of my pants. Depends on my mood and energy level, depends on leftovers from our dinner the night before. I almost always say at pickups "xx had a great day, no issues, had xx for lunch today."
Most parents really DON'T care but there always seems to be ONE anal parent who does.