Overall: I think there are the bones for a strong story here. I love the moments of conflict where the unwelcome stranger makes its presence known, and the chaos of the phone ringing at the same time as the knocking restarting provides for a good scare and threat to your protagonist. It has a good stranger-danger and 80’s urban-legend feel to it, but in a potential second part of this story, I think you’ll need to depart from that feel a bit to make the story feel unique. What will be your perspective that sets your tale apart from the arch-type we all know? You’re around 1,400 words here, so there’s room to put your stamp on it.
Setting: Well done, I feel like I was dropped in the Byers household from Stranger Things!
Characters: Debby embodies the role of caring single-mom well, but not much to her beyond that yet. Not a criticism, as your focus needs to be on your protagonist, Eddie. Eddie is certainly smart for a fourth grader, and competent; but what is making him tick, what are the goals of the protagonist? I would like to know him more, and have him act rather than just be acted upon.
Plot: Straight-forward, but effective! The “stranger at the door” story fits the setting well. As mentioned above, I just want to see you put your own unique twist on the story! This could take the form of making the antagonist more present to the story, or focusing more on the threat to Eddie, rather than having some of the action take place while he sleeps. That being said, I loved the discovery of the personal message Eddie finds while on the bus!
There are a few more general, easily edited things to fix.
“Eddie’s head snapped in the direction” should be something like “Eddie snapped his head towards the sound.”
And there are four instances where you use ellipses when Eddie is speaking; may want to consider cutting this down to one or two.
But keep going, a promising draft!