I did a little digging, because I suspected the director dressed the man in the car exactly like the man on the dock with reason. Sure enough, in the script, it indicates that the man in the car was the man on the dock.

Now yes, it could be a paranoid hallucination, I suppose. But the question at the film's resolution isn't "will she escape?" The question is, "can she live?" We get a definite "no" answer-- she's under the cult's control at the end, either literally or mentally.