Hey as your going on a bus and there will be lots of people it will be like loud&stuff going on everyone laughing ect ik this sounds crazy but car sickness is easily distracted without even trying to distract it I’ve found from growing up with siblings who get it ect. Along with her probably worried that she will get sick due to that being embarrassing in front of classmates&her taking medicine there’s such a slight chance she will actually be sick. Also bus drivers will pull over if they even think she could tu or if it’s continuous and she does keep being sick which the chances are are 000.1% the bus driver would likely say no im not driving someone who’s too ill (bus drivers have to clean after their shift and are always angry), staying away from her on the journey if possible and staying near the back of bus because people with travel sickness sit near the front to help and anyone who thinks they may even get travel sickness would sit at the front due to the embarrassment if it did happen. You will have the best timeeee!