Did I over-React???

[Crayola kiddies]

Am I right to feel a bit upset that child C's parents haven't called to discuss or say sorry for behavior? or ask after the injured child?

I think that you are looking for the parent to validate your concerns and therefore reaffirm that you did the right thing by sending all the kids home. To me it seems the parent has already demonstrated how they feel about it. However you are entitled to feel how you feel regardless if its right or wrong.