there is always bunch of farmers who are mass killing all mobs incl. quest NPC’s and you can’t talk to them but it seems devs don’t care that players can’t continue with Venthyr campaign.
So if it happens to you I would advice to pick Chancellor Ylenia , she is hidden in small chapel and should be alive.If you already picked ‘wrong’ NPC, try switch war mode on/off and hope for more luck.