This would be difficult. Honestly, i say that Darui could give a good fight. I just can't see him win in this scenario. Darui could probably solo them, but 2 on 1 is too much in my opinion. Haku and Zabuza working together would be a water/ice explosion. Not to mention the mist jutsu they can use to their advantage. The only way to win this type of match up is to find a solution in defeating them quickly. If Darui lets the mist jutsu spread for too long it's over. Haku is dangerous because of his Senbon and Crystal Ice Mirrors. Haku can strike at any given moment, but having lightning in his arsenal is good. I just can't judge Darui that much. He's not bad as a ninja. He has a lot of affinities a total of three. So he could kill one of them or injure them badly.