When villain checks the turn, I think it's rather likely he has some sort of weak made hand or he has given up.
Our range is pretty strong for peeling the flop, we pretty much always have a pair. If he has a value hand, I see no reason for him to shut down on the turn. The 9 hits 99, so one set gets there, but in his eyes we pretty much have pairs here all the time. We might have QQ and slowplay, which would make sense, and we probably have a lot of QJs, KQs, AQs in our range as well. I think he has given up when he checks the river, and will have hands like maybe a weak Qx which he bluffed preflop, a 9x type hand and air (AK, AJ, AT whatever). Overpairs would probably go bananas on this flop, so I doubt he has those. I've seen some players cbet the flop here with hands like JJ just to shut down later on as well, so he miiiight have those.
The amount we should bet on the river, vs. a range which either is complete air or a weak made hand should be something like $12 - $16. I'd consider shoving, but without knowing anything about the metagame that has happened between Tom and the villain, I think I'd rather go for the smaller bet on the river. With this betsizing, I'm hoping to get a call from his weaker showdown hands. If he has trips with the 5, he's losing all his money anyways.
So, his range on the river is like weak showdown hands like pairs and ace high, although A high doesn't have a ton of showdown value, but it looks like it does. Maybe he has a hand like 65 from time to time, but 5x is shoving the river anyways so betting small is cool.
I don't really like shoving the river, because our range is pretty strong. We don't really have a ton of floats in our range and we can easily have a hand like AQ or 65 in our range given the price on the call preflop, and we can happily jam it in on the river because we know that his range is crushed by our range.
So again, I think the best betsize is like $12 - $16. I like the number $15 here. Weeeeeeeeeeeee. This post was shorter than the first one!
Oh yeah, I think he's likely to 3bet suited connectors and stuff, which is why I say he can have 9x or 5x here.