Based on the story provided, Mr. M appears to have taken Ms. C's lunch, as indicated by the spaghetti sauce stain on his shirt and his suspicious behavior.
Based on the short story provided, it seems that Mr. M took Ms. C's lunch.
There are several clues pointing toward this conclusion.
Firstly, Mr. M had a fresh spaghetti-sauce stain on his shirt, which coincides with the spaghetti and meatballs Ms. C had for lunch.
Additionally, Mr. M's quick, dismissive response and the subsequent knocking over of his lunch box suggest he's hiding something.
Lastly, Mr. M was reportedly in Ms. C's room before lunch began, which would have given him the opportunity to take her meal.