Coach, you haven't stated which rules you're using.
Under NFHS, the try ends when it is apparent that the kick will not score. 8-3-2 So after B blocked the kick, they recovered a dead ball. And B cannot score during a try under any circumstances. 8-3-3
Under NCAA, when the kick lands in the EZ, it is dead by rule, and the try is ended. 8-3-1 Once again, B recovered a dead ball, though in NCAA it IS possible for B to score during a try.
So although the basis is different depending on the code, it sounds as if the result was correct.