Maybe my wording was not clear, but indeed you cannot get the hair if killing Ethel. And you even cannot get the Spellthief bow if you kill her by shoving her into oblivion, what maybe should be avoided.
You can get the hair with the option that she sets Mayrina free (if you roll appropiately) or the option that she keeps her and the baby. In both cases you can still kill her or not. I always kill her because in my opinion she is too much of a danger for the world (I'm not a DnD player but my char may be chaotic good (?) if I got that strange alignments right, so independent of class I play I cannot accept such a deal). So I always get the xp but not the ability point, but that's life. I think the xp should also be applied if you do not kill her, it's a valid solution to the situation from the dialog.
