So many solutions...

Your PC seems to have forgotten the obvious: There is always someone more powerful. Realistically, if there is a vampire running about and kidnapping innocent villagers, sooner or later some good NPCs are going to hear about it. Think about it: If your PCs were an NPC group, a group of good PCs would be all over this! Unless adventurers are quite rare in your world, some high level paladin, cleric, or other strong NPC is going to try to hunt her down and kill her.

What is the rest of the party like? If you are not running an evil campaign, it seems unlikely they'd stay with her. Even a callous neutral party would probably find her behavior far too vile with which to associate.