Prior to checking the turn I'd say his range is.
77-JJ perhaps AsQs/AsJs or a couple of AsQ hands.
Here are some ranges. I think I was a little generous including 66 in the best case and not including QQ in the worst case. But meh maybe a few AsJ hands could have made an appearance.
Worst case scenario
Hand 0: 29.679% { AcTc }
Hand 1: 70.321% { JJ-77 }
Best case scenario
Hand 0: 38.091% { AcTc }
Hand 1: 61.909% { JJ-77, 6c6s, 6d6s, 6h6s, AsQs, AsJs, AsQc, AsQd, AsQh }
I check/fold the turn. Sure the rare flush draws will bluff us but 99 probably isn't betting. I bet bigger on the flop, there is a fish to value town.
As played I check/fold the river. All we fold out is half the JJ hands. Flush draws made it, fullhouses beat us and 99 probably weren't betting the river.