This is a good example of not only reading the rules, but comprehending what you read (and not reading anything into them). That includes referring to other related rules.
Don't have my book handy so I can't quote - but it clearly states that on touchdown plays in which there is a foul by B, A has the choice of enforcing the penalty on the try or the ensuing kickoff. (same holds true for a TD after change of possession).
Since it doesn't say B can do the same thing, then B can't do it - just like they can't shoot a runner with a shotgun to prevent him from scoring. You won't find that in the rule book, but it can clearly be inferred in the equipment rule.
