On the river it is a close spot only straight and better hands then yours should actually call a raise on the river I don't think villain can have a good enough Kx hand to call a raise here.

There are T9s and 54s or 8 combos you beat and then there are the combos that beat you such as 87s 2 combos and 86s 1 combo, 88 1 combo, 77 1 combo and perhaps K8s but then also K7s comes into play although K7 might not call a rive raise. Think making a raise on the river is +EV play as you don't want that the straights fold shoving might be overdoing it so would make it $12-$15.

Villain doesn't have kings because he flat pre. Villain shouldn't have K8, 88 or 86 because they called flop so hands that beat you which make sense are 87 and 77 which is 9 combos if they have all the 87o. If on the flop villain calls only his gutshots with a backdoor flush then you still have 50% against a range of straights and boats so worst case scenario you're breakeven with a raise (unless they're folding straights here so if villain is an ultra nit this is less attractive and you should start bluffing them tons). If we start to add in any other combos of T9, 95 or 54 then we're ahead of villain's range so I think you should be raising in this spot. Also I don't think this is a turn for villain to develop a leading range on so we can safely assume that villain is a fish and will not be making any big lay downs.

Seems like a shove to me, straights are very possible for villain to have and he seems to be a fish with his line aswell (not that the line itself is necessarily awful, it's more the fact that regs are generally not leading pot and betting pot on the river in any spot).

Without any info i'd just call here. The thing is tho the turn donk seems fishy, villain just might be playing unbalanced at these stakes. Looks very much like he hited a 7 on the turn for 77. I'd say 9 10s its less likely, cause most of the time you want to 3 bet these hand to be profitable oop.