How can I help my mother's stresses about work?

It’s been brewing for awhile now, but lately it’s been getting worse. I’ll give a little backstory to help explain and get the whole picture. I really need some help with this.
My mother drives for a medical transport company in Vancouver, Wa; a wheelchair van. She likes the work and the people she drives, for the most part. She’s really easy-going and can put up with a lot of flack. She works between 8–11 hours a day depending on the appointments of the clients. We usually have dinner waiting and let ther relax when she gets home.
Lately, she’s been getting really upset about work, one other driver in particular. Ths person is the last to leave home and the first to get back. They all get paid the same so when one person works a 6 hour day and another works a 11 hour day, it’s really upsetting. Also this person is quite the gossiper and has been saying some very not nice things about other drivers.
I’ve been doing my best to just listen and be there for my mother. I understand what she’s going through and I try to help as much as I can. I’m just concerned that this is going to get worse and I was wondering if there is anything else I can do to help, even if it is just to stay out of it.

This isn’t a coincidence about this question’s timing and mother’s day. I just thought of asking it today