i think you should go to the school and talk to the principal, and if allowed, speak to the concerned kids in front of the principal. kids can be really cruel and spiteful. having veg or non-veg is a personal choice and should not be dictated. and it is definitely not alright to taunt or bully someone about their eating choices. and this type of behaviour needs to be stopped at the earliest. a veg friend of my daughter used to taunt her saying she is a murderer who kills innocent animals. my daughter was appalled and used to cry a lot, and wasn't able to eat meats. i spoke to the girl and explained to her that it was wrong of her to speak like this.
Well..I have faced that too! I was raised in a largely vegetarian place where non-vegetarians were looked down upon. You should tell your daughter that every person and family has their own food habits and that she shouldn't be ashamed of her food habits. Tell her that she isn't consuming non-veg food in front of them and so it hardly matters! I know your child is at a sensitive age and kids can be very mean when they taunt. Even my kids though being raised in a cosmopolitan environment are teased by some of their veg friends!
It is disgusting that now kids are being bullied and looked down upon for their eating preferences. I think you should meet the teacher in the school and immediately bring up this thing in their notice so that they take action. As far your kids are concerned make them understand that no one is good or bad or can be looked down upon because of what they eat or do not eat. Boost their confidence so that they are not bogged down by such stupid inferences.