Did person A raise preflop?

If not, its his own fault that he lost. If he had put a decent raise in then on his all in, you could have put him on AA KK or such and laid it down. He slow played pre and post flop, thats just asking to get drawn out IMO.

Even still, a push-check reraise after a bet and raise should indicate alot of strength and not a bluff outside of any info on how he plays. Personally, I would probably have put him on hitting a low set the way he played it, and laid it down after his push. Its still not a horrible call based on the money in the pot