Hmmm, not too sure what the law is on Person C intervening in a case where Person A is threatening Person B, probably depends if Person C has a clear way to leave the situation. Is she being charged criminally or is it a civil action? Because if the drunk guy told the cops he wanted to press charges, they would have to send it over to the Crown who then figures out if there is evidence to support charges being laid.
Either way, crappy situation and I hope it works out.