<<Spoilers>>

Got the humans to fight the orcs, but at then end when they were all together I killed all of the mountain men as well since they are bad guys. I guess I was supposed to talk to them. Any other way that I can complete this quest or will it be stuck in my log?

Thanks!

What happened with me was that there was a new set of Mountain Men after the battle, waiting near the West side entrance to the town IIRC. I talked to them to complete the quest, and then I attacked them after.

But I'm not sure if that new group of Mountain Men still appears if you attack the Mountain Men during the Mountain Men vs Orcs Battle. Looking for them in your game is worth a try at least.