Why she's the killer: The way Nolan dies is the exact way Caitlin fantasizes about killing him in the woods. Coincidence? Maybe not. Nolan is also blackmailing Caitlin with photos of her mother cheating on her other mom. If the photos were to leak, it could ruin her mom's entire political career. Maybe she's doing all of this to protect her family's reputation.
Why she's not the killer: It seems a little too easy that the person who predicts how Nolan will die is actually the killer.