The child was holding grandmas hand the whole time it walked up the wall and fliped over. It's quite easy to walk up a wall and do a flip when you're braced against someone. No supernatural forces neccissary. Just everyday physics.
Also, black flies exist independent of the occult.
Stairs creaking are part of the natural world. Not the supernatural world.
It is possible that there was an ACTUAL man standing in her bedroom when she woke up. A naturalistic explination is far more likely than a supernatural one. Though, as she had just woken up, it was quite likely a hypnagogic or hypnopompic hallucination.
The girl levitating is the only one that I think would actually qualify as being "supernatural". And of course, this is the one where only once person witnessed the event. There are several possibilities here. The mother could be outright lying. The mother could be exagerating what she saw (during exocisms "levitations" are anytime a majority of the body is elevated, like when only your head and toes are touching the bead. Levitation does not mean completing floating in the air). Another possiblity is that the mother was experiancing some sort of psychosis. And finaly the last explination is that an actual supernatural event occured.
Out of those options, which one is most likely? And which one is the least likely?
Lying, exagerating, being mistaken, and hallucinating have all been demonstrated to occure. That is why those explinations are all known to be possible. The supernatural explination however, has NOT been demonstrated to occure. Thus we cannot definitively say that it is possible. And I'm going to put my money on possible events as more likely explinations than events which have not been shown to be possible.
*before you even try to go there, I am NOT saying the supernatural is "impossible". What I'm saying is that in order to make the claim that "something IS possible" you must have either precident or something of parallel comparison. Without either of those, you cannot know that a thing is possible.