I think the witch can do many different things depending on different circumstances. In the 19th century she ritualistically disembowels the men at castle rock. In the early 20th century she haunts Rustin Parr driving him insane and coercing him to commit heinous acts. And then theres Mary Brown's unexplainable…

but what about the bundle of sticks and fabric that heather finds with bits of josh in it? it suggests something bad happen to him. also, once they reach house, in one frame, you can see the torn up remains of josh's flannel shirt. i mean its not proof that its not Josh, but it leaves the question open