Is river an easy call? See below for flop comments.

100NL - Full Ring

Hero is CO ($100) with
Villain is BB ($41.25)

Pre-Flop
UTG calls $1
MP1 calls $1
Hero raises to $5
Villain calls $4
UTG calls $4
MP1 calls $4

Flop (4 Players, Pot = $20.50)


Villain bets $5
2 folds
Hero calls $5 (What should I do here? I had seen villain donk with pretty weak pairs already. Is calling best here since I don't want to play for his 40BB's yet? Or should I want to play for his stack?)

Turn (2 Players, Pot = $30.50)


Villain checks
Hero checks

River (2 Players, Pot = $30.50)


Villain bets $7
Hero calls $7