Villain is relative unknown, but 36/25 or so after 40 hands. What are the best and worst hands that I should have on the river here?

PokerStars No-Limit Hold'em, $0.50 BB (9 handed) - Poker-Stars Converter Tool from FlopTurnRiver.com

MP2 ($70.45)
MP3 ($57.15)
CO ($48.50)
Button ($49.75)
SB ($115.65)
Hero (BB) ($51.50)
UTG ($43.85)
UTG+1 ($26)
MP1 ($50)

Preflop: Hero is BB
3 folds, MP2 calls $0.50, MP3 calls $0.50, 3 folds, Hero raises to $3, MP2 calls $2.50, 1 fold

Flop: ($6.75) 3, 6, 9 (2 players)
Hero bets $4.50, MP2 calls $4.50

Turn: ($15.75) 2 (2 players)
Hero bets $10.50, MP2 calls $10.50

River: ($36.75) 2 (2 players)
Hero checks, MP2 bets $30.50, Hero calls $30.50