USC on last play of game

[Theisey]

You say there was a personal foul during or after the TD was scored?
Forget about the taunting (UC) foul for the moment as that foul would be enforced as a deadball foul at the succeeding spot.
It makes a big difference to know when the foul OOB happened.
If the OOB foul was before the apparent TD, the TD is wiped off. Team-B would get a chance to snap after enforcement.

If the OOB foul was after the TD, then the score counts. The fouls need be enforced on the TRY as the game is not over until the TRY is completed unless the youth league rules do not require it to break ties for playoff purposes.