c/f river
+1
Its kinda close imo. If you were more sure that he's bluffing at every pot when he's shown weakness then I think you can justify c/c. Villain not being able to have the

in his hand and the fact that you don't really have much to go on makes it a c/f imo.
I know it really sucks to fold top pair when he might be bluffing but in the absence of a decent read and us having blockers to a lot of the combos of bluffs he can have its gotta be a c/f imo.