I have watched hens with baby chicks. When another hen gets too close (3 feet seems to be be about the limit), momma hen chases them away (out to at least 10 feet). Same if another hen pecks a chick. But it seems to happen multiple times every day.I don't think your hen will connect your hitting her with her attacking your child.... chickens are not dogs or horses etc. They are not that easily trained... As far as discipline I don't think they connect their bad behaviors with it.
So if you just want to act like momma hen, you should stay near your "chicks" (children), and chase the hen away every time she comes close--and be prepared to do it repeatedly, every day.
It looks to me like chickens test or reinforce the pecking order in small ways many times every day, so I think it will be an ongoing problem unless you rehome the hen (to the farm or the stewpot.) Or keep her and the children separated by a fence at all times, unless you are standing right there watching to drive off the hen if she gets close.