Easy enough to get to the cure, a few rougarus and skin-hunters might slow you down a bit, but snagging it and getting out alive is just a teeeeensy bit of a challenge. Three gunslinger ghosts and a good number of spirits are watching over the cure and there is almost always at least one of them looking in the direction of the cure. Dynamite helped for me. *Alternatively you can use the Chicken Feet Necklace to avoid combat completely with the ghosts.

*thanks to Rego for that info

Once you have the cure you're free to give it to either Annabelle or the priest but whichever you choose be warned you will lose access to the other afterward.