Last session a long-known NPC just showed up in our hotel room, bitten and level-drained from 5 to ~2, asking our party for sanctuary from a vampire. We do not wish to face a vampire but will if it makes a nuisance of itself. We want nothing to do with this vampire and would prefer to avoid it. Our drained NPC 'ally' may be a charmed agent of the vampire, or maybe not - we've made no assumptions.
We already loaded up on holy water and wooden stakes, just in case. Also we immediately traveled overland 10 miles, with our drained ally, in an unpredictable direction. This is a well balanced 6th level party. PCs include an enormous low-will Rage Monster, a positive-channeling martial Cleric, An Arcanist, a martial Warpriest, and a Psychic. The party contains no good-aligned PCs, and mostly neutrals. What other plans and preparations might we reasonably make?
Already done: Cleric switched around spells to prepare Communal Protection from Evil and Align Weapon. Warpriest also prepared Communal Protection from Evil. This because the PCs know the worst danger from vampires is their domination. The best Knowledge(Religion) roll to know about vampires was a 23. We guess it's a spell-casting master vampire, with servants, but we don't know. It's probably already noticed our existence. I suspect GM will play it as a long-running off-stage villain.
Besides these rudimentary steps, what else might reasonably cautious PCs do to prepare for possibly being stalked by a master vampire? What can we do to protect our resting place?