First of all, in the case of carrying passengers (non-profit), then the driver at that time should be responsible for the safety of passengers. So, it's a pity that your classmate's uncle is in charge of the safety of the people on the bus. Although he has passed away, his legacy can still be paid accordingly. Of course, all the people who died here were relatives. I think the general issue of civil liability compensation should not be involved for ethical reasons.
Secondly, the insurance company's compensation. Here, let's see what insurance companies cover. 1. If it is the car insurance or personal insurance of his deceased relatives (the beneficiary is not her), it has nothing to do with your classmates. Of course, she can ask menstruation, the heir of the insurance money, for the compensation mentioned in the first point. 2. If your classmate has personal insurance, just apply to the insurance company according to the degree of her injury, and pay attention to keeping the documents of each medical expense.
Third, I didn't find any responsibility in your statement. Naturally, there is no need for compensation, but as far as I know (as I mentioned above), the university provides medical care for you, so there should be no problem with your classmate's medical expenses, and the school can reimburse part of them.
Finally, according to what you said, your classmate was overloaded, which was at fault. They ran into a overturned coal truck. I think the relevant transportation departments will identify the responsibility for the accident. If it is a secondary responsibility (or the coal truck overturned without any warning that ordinary people can notice), you can still try to claim medical expenses, funeral expenses, lost time and compensation from the unit to which the coal truck belongs.
Finally, I wish your classmates a speedy recovery and a good life.
Another point: if you want to claim compensation from the coal truck, you need to bring a lawsuit within 1 year from the date when you know or should know that the damage occurred, otherwise you will lose the right to win the case.