brake rotor

Please provide some details. Is this with the wheel on or removed? What symptom are you trying to solve? Is this a new rotor?

when driving something fell off and started making a grinding sound. It was the caliper pins that had broke off. when the wheel was removed the rotor was very loose and the part store said maybe the wheel bearing hub needed to be replaced. could this be possible? or is there something else that it may need to hold the rotor on?

You are describing two different problems. The rotor is held tight by the wheel and lug nuts. It is not uncommon for a rotor to be loose and flop around when the wheel is off, unless it is rusted tight. If the wheel bearing is bad enough, there can be looseness in that too, but you will be able to wobble the entire wheel/tire around when the lug nuts are tight. You would have heard a buzzing noise, similar to an airplane engine, long before the bearing became that sloppy. It can takes years to go from a buzzing noise to sloppy, and the van would have been really miserable to drive like that.