Villian is lag but has been a little tilty after some bad beats and is playing more loosely than normal.

.5/1 (6max)

Preflop; hero dealt 5d5h is sb
CO raises, Button calls, Hero calls, BB folds

Flop (7sb) 10c 7s 3h
Hero checks, CO bets, button folds, Hero calls.

Turn 10s
Hero checks, CO bets, Hero calls

River 4c
Hero bets with the intent of folding to a raise.

Is this line ok or should I have gotten more agressive on that fairly safe flop?
Is c/c on the river better?

Is he playing more aggressively as well?

I don't mind the flop. I like to see the action with a weak pair. If button raises CO, I'm done with the hand.

Since CO bet, as he would with any two cards here, and the turn paired TP, I would think you are ahead more often than not on the turn. I would c/raise for value, maybe folding to a 3-bet if villian hasn't been getting out of hand with his aggression.