Mia didn't have her best friend, Laura, here but she did have a purpose. Seeing humans interact with her, and that was something important that she could take back with her.

"I'm curious. Did you know your best friend was missing while he was here and you were home?"

Ned was the first person that she'd met that was close to someone that was here first. Would her family miss her, wonder where she was, or was another version of her there while she was here?