They’re presenting Charlotte as a reformed bad guy, so therefore there’s no reason why she’d leave the house to meet someone unless it was a) someone she trusts, or b) someone who she wants to make amends with.
People she would trust:
- Ali (can’t be Ali, she was at home with Charlotte)
- Jason (he’s “out of town” but no proof on that)
- Dr. Rollins (this is a likely possibility as there have been hints that Uber A is…ugh… a new character)
People she would want to make amends with:
- Hanna, Emily, Spencer (they were in the hotel all night)
- Aria (she left the hotel room but obviously it isn’t her because if it was, we wouldn’t find out about it in the second episode of the storyline, and they’re talking about it next week)
- Sara Harvey
With all of that in mind, my suspects are Dr. Rollins, Mona, and Sara Harvey. It’s far too early to think about motive. The only one with a true motive right now is Mona, but I’m sure we’ll have potential motives for the other two soon.