I like the ending on this one. It leaves the conclusion pretty up the air, lets you draw your own conclusions about what happened during and after the fade to black. I liked it when The Sopranos did it, I always interpreted that ending as being a sort of commentary on the inevitability of Tony's death: it doesn't matter who does it, or when, or how. So long as he's in that life he'll always be looking over his shoulder. Similar here: it doesn't matter who's at the door, really... she'll spend the rest of her days second-guessing every doorbell.
Something else I'd point out here is the lack of the "sin-punishment" cycle. In stories like these, ghost hauntings are "punishments" for past karmic "sins". The comments here are sort of trying to reinstate that order by positioning the ghost as a corporate stooge, or that the woman's sin was looking too deeply into things. I think that in this case, it was more like a natural disaster... she got caught in bad weather, that's all it ever was.