The scariest monster of them all? Surviving the 1630s. The lighting rod that pushed “The Lighthouse” director Robert Eggers into the spotlight. “The Witch” navigates the uncharted wilderness of the early days of America through the eyes of one devout family. When things go awry for the isolated group tensions fly along with plenty of accusations. But who’s really to blame when the crops go bad or the milk dries up? Is it fate or something much more nefarious?