Penny had been waiting for Charlie's arrangement.
She would rather not leave with the other evacuees to some unfamiliar place, as she would rather stay with Charlie to prove her worth.
After all, she was well aware that she had no way of removing Fleur's poison from her body and had to pin her hopes on Charlie.
However, if she became worthless to Charlie, he wouldn't have a reason to save her.
A year would pass in the blink of an eye, and she would definitely die without the antidote.
As s