My ds rode the bus in K. He was the only kid in the mornings, but it was full in the afternoon. No stops between the bus stop and school, on the way back there was a stop in between school and his stop. He knew what his stop looked like so I wasn't worried about him getting off at the wrong place. His ride was pretty short and he handled the noise fine.
i would make sure she knows what her stop looks like--find one thing that stands out (pink house, big rock, etc) and tell her to check for that before she gets off. I would also make sure she has your cell number and home address memorized. I still check with my ten year old periodically to be sure he can answer those questions correctly. We have also talked about what to do if he gets lost in any situation--find a store or museum or amusement park employee and ask them for help. If that's not an option, find a mom with kids and ask her for help.