A22's action is a live ball USC, assessed from B-5. If accepted (which it will be), the TD does not count, and the next play is from B-20.
We do not know the down or distance, so I can't say which down it will be, but we do know that it remains A's ball as the USC does not include a loss of down provision. Edit: I've just realised that the 2/3 means 2nd down 3 yards to go. As the enforced USC penalty still leaves the ball in advance of the Line-to-Gain, the next play will be 1st and 10 for Team A. We assume time as expired, as there was 35 yards gained, and only 0:03 on the clock at the snap. Thus, this will be a period extension for an untimed down.
As no foul was described, B78's helmet coming off is the responsibility of B78, and thus, B78 must sit out the next play. The 2013 rule changes still do not allow B78 to re-enter the game, as the timeout was taken by Team A, and not Team B.
So, the officials should not have allowed B78 to participate in the next (FG attempt) play. But since someone missed this (probably due to the Team A coaches' conference

), we need to decide what to do next.
Assuming the participation by the temporarily excluded B78 was detected after the play, we have to determine what the status of B78 is. 9-2-1-b provides for a dead ball unsportsmanlike conduct foul if a substitute (which B78 technically will be) is on the field of play. But, the spirit of 9-2-1-b to me, is more directed towards a non-participating substitute. B78 participated and influenced the play. Thus, I'd go more by 9-2-3-a "While the ball is in play, any person other than a player ... interferes in any way..." - and rule an unfair act. In that case, I'd disqualify B78, and impose a 15 yard (converting to half distance, since the previous spot was on the B-20) automatic first down, and extend the down once more for A's ball on B-10, 1st and goal.