Illegal Block or Contact
ARTICLE 4. A player of Team B who has made a valid or invalid signal for a fair catch and does not touch the ball shall not block or foul an opponent during that down (A.R. 6-5-4-I and II). PENALTY—Free kick: Receiving team’s ball 15 yards from the spot of the foul [S40]. Scrimmage kick: 15 yards, postscrimmage kick enforcement [S40].
so, as I understand it, if not in the EZ, this would be PSK, because: 1) foul by receiving team, 2)during a kick that crossed neutral zone, 3)K would not be next to put ball in play.
Since it is in the EZ, since B touched it, it is a live ball, recovered by A in their end zone, they would decline the penalty, resulting in a TD.
*I did have this wrong as I neglected to account for B's touching, and modified to be correct.