No point in blaming Nimboli. We know the reason why she compared about the food. Sowing seeds of hatred is become Mangala's nature. She doesn't know difference between going to school and taking a small snack box.
I agree with the tiffin box contents. I think they should've added a fruit like some apple slices along with so it doesn't matter. As a serial they are also promoting healthy habits so maybe a fruit or even a paratha may have been a healthier option.
Mangala doesn't know difference between ladoo and apple. The ladoo in that box is just a small snack where as the A for Apple will go a long way in Nimbolis life. She herself hasn't a clue but surely she knows education and school is important. From which angle was she saying that she will send Nimboli to school. She's so insecure that she can't see anything beyond Anandi hugging Nimboli and keeps planning to keep them away.