Halsin will be in the emerald grove if you kill the goblin leaders and THEN go to the worg pens. If you sided with Minthara to do the raid on the druid grove, all the NPCs will be dead and you cannot complete that quest, you have to do everything a different way.
If you kill the tieflings and druids, or they dies in the raid, Karlach will not join you, and if she's with you at the time it happens, she leaves. If you stole the Idol of Silvanus for that one quest that you get (can't remember circumstances, I think one of the kids asks you to?) the druids kill the tieflings.
It sounds like you made an evil decision somewhere, somehow.
