Board Thread:Morrowind/@comment-199.116.155.78-20130317194648/@comment-4787430-20130317195317

Did you check the corpses of the dead Glenmoril witches to see if they still have their head attached?

Glenmoril Coven doesn't respawn, so if you can't find a witches head on one of the corpses, then you are out of luck.