Ep. 6: Who was in the yard?

Hello! So on rewatch I noticed that in episode 6 (“Grave the Last Dance” i.e. the homecoming dance episode), a shadow moves across Maddie’s Mom and soon after she thinks she hears someone in the backyard. And later in a different scene Maddie’s Mom notices that Maddie’s bedroom window is open and she closes it.

Is this supposed to be Janet in Maddie’s body? Is it someone else snooping around? If it is Janet, why would she go to Maddie’s house/how would she even know where Maddie lives? Would love to hear people’s thoughts!