Not the most exciting of endings and fairly predictable.  I didn't see the dual nature of the witch until the end, so that was good.  The main thing I had an issue with was the professor who thinks he knows who the witch is and the witches seem to know who he is as well, but no background information is ever given on this topic.  Also, the jump for the wife to think of witchcraft seems a giant leap as well.  An okay episode, but not that great.