I would say the correct answer is B ("I am sorry to hear that; but why did not you tell me that before? If I had known as much this morning I certainly would not have called on him. It is very unlucky; but as I have actually paid the visit, we cannot escape the acquaintance now.")
It is both false and ironic because he would certainly have called on him nevertheless, regardless of the fact whether his wife likes Mr. Bingley or not. He didn't really do much about the whole affair, which is ironic because he makes it as if he had.
