The oil change price is on the top of average, but not excessive.
If the oil pan is rusted the motor has to be lifted to remove it on a Cummins, and the pans are 400ish without labor. I would be surprised if it's that rusted, but who knows.
The wheel bearings, as mentioned, are common but that seems a little steep. If you live in the rust belt, oil pan??, then the shop could have experience and quoted 4-5 hours per side, or more. They take some effort and time to remove on a non-rust belt truck. You don't want cheap wheel bearings, they should last 80-150K miles under normal use. Be sure to change the front axle ujoints at the same time.
The cost at a dealership for both sides should be around 1500-1700.
For the kind of money she was quoted you could buy a spin free kit, install it yourself and save money.
If the wheel bearings are indeed bad I would park the truck until fixed, they fail rapidly and can compleatly seize up.