It doesn't matter which daughter was at the game with her, I'm sure he wasn't privy to which family members were going to that game, and most people wouldn't have known that either. This, combined with the fact that her older daughter was knocked up already should have made it obvious who he was referring to. This, plus common sense, of which none of the people in that family seem to have much.
But I was wrong about one thing. It was only the idiot tool husband who actually used the word "rape", so I was incorrect saying they both accused him of making a rape joke. It was only the male tool in the family, technically.