During a game I had last week, the coach from team A is crouching in front of his bench talking to a player. The benches are very close to the floor so the coach's feet are on the court.

Team A is pressing and B1 takes the ball up the sideline in front of A's bench. What should be done if B1 ran into the coach?

It didn't happen but we weren't sure what we would do in that situation.

Without a doubt - T

Rule 10.4.2