They both tried several moves to beat their opponent. B is making an attempt to bring A back down to the mat with no success, but he is not trying to do a heelblock and pull back. These kids don't understand stalling at this point. Their motors are going a hundred miles an hour. If all kids would go as hard as most junior high wrestlers, you wouldn't hear all the complaining about stalling at the high school level.
Coaches start hollering, kids get frustrated, it can be a tough call.
If I think it is necessary, and if there is an out of bounds, I tell the top man that he needs to take the man down or cut him when they reach that position. If the bottom guy is standing a squatting I tell him that he needs to work something off of the standup and can't just squat. They usually understand. If he pushes his opponent off the mat he could get zinged for a point. I have told him to take his opponent to the mat or cut him.