So.
Ideally she'd want to bring as much stuff as possible, but that requires money she currently doesn't have because she spent almost all of it on her travel. She's also probably going to be grounded for several decades at least a day.
She can definitely charge her phone and load The Whole Of Wikipedia on it, then - does she still have her otherworld phone? No, it was on her nightstand. Very silly of her, it would have been some kind of proof that she can communicate with the other world - she totally needs a better name for it.
Bonnie can definitely put some of the books she's less attached to in her bag, fully charge her power bank and try to remember also grabbing it, what else?
Probably some stable food? They seemed to have different cooking traditions, so it's probably worth it to exchange.
Oh, her English book from middle school! It's structured for learning, so it will be super useful to teach it to other people. Actually, a book about Italian for foreigners would be more helpful but she doesn't have that.