I have no problem raising in position with 5
7
. It's the kind of hand that pays huge when you hit. Along those lines, when you flop "only" one pair AND an Ace hits the board, this is the time to slow down when your c-bet doesn't drag the pot immediately. Once you fail to improve by the river it's not a spot to be committing any more chips in.
After MP quickly bets out $75 on the river, there aren't many holdings you are actually beating - I'd fold with confidence unless you had some previous history with villain that would lend itself to a better soul read.