What happened to the twins in the movie witch?

What happened to the twins is unknown since no explanation was given. In the scene after the night in the barn when one of the witches sucks (or whatever) the goats milk they are not visible. All one can do is assume they were taken by the witch or witches.

What happened to Caleb in the witch?

After a brief disappearance, Caleb appears back at the farm, “naked as sin and witched.” He’s comatose, mumbling, covered with mysterious cuts and having some kind of fever dream. He coughs up a whole apple covered in blood, has a moment of religious ecstasy, then dies.