Firstly, bus monitors are there to Monitor the children, seeing if they are violating safety precautions and also the driver's driving habits. They have no authority over the children on the bus. They are there to keep the smaller children out of trouble or may not know when to get off the bus, or special needs that doesn't require a special needs alternative transportation. She isn't paid to be an authoritative figure, that is left to the Driver and the School's administration, she is low woman on the ladder as far as that is concerned. So those of you that say she needed to become that authoritative figure have it wrong - she had no authority to begin with.
Secondly, there is a group mentality going on, all of them may have not even been friends, but wanted to fit in or try to form a connection. It wouldn't have mattered if she did say anything, as you saw - she tried and they laughed and completely overlooked it. They had no respect for an adult.
Bus Monitors aren't specifically trained, they are placed there because there is a need for bus monitors. It would take training to deal with that sort of harassment and I feel she did all she could do. The stance you're taking is that she should have stood up for herself. She is also an old woman probably too old and overlooked for most jobs. Pretty much what got her the job is that no one else wanted it or that she seemed to have the patience of a saint. So I don't get why we are here talking about her as a weak human being. She is stepping out of her comfort zone and working a job that she probably doesn't want, but has to have. It is easy for all of us to sit here and say that she was weak, but we don't know what sort of life she lived before this.
The teens were cruel, there was nothing she could have done... and if she did, she would have been the one who got into trouble or lost a job she probably needed. None of us can say we could have handled it, so to say she should have handled it BETTER is a bit narcissistic and shows that our judgments can be just as cold as the teenagers on the bus.