Pharmacist here.
CIII - CV meds (diazepam, vicoden) can have a max of 5 refills, up to six months. They are controlled, but not as much as....
CII meds (oxycontin), which have no refills and are tightly controlled.
What I didn't see from the initial police reports is whether or not the prescription medications were in legitimate bottles, with a trackable prescription number on them, thus, written by a licensed prescriber.
A hundred diazepam in a baggie certainly did not come into the user's hands legally. Although, a legal prescription bottle doesn't 100% indicate the prescribing was for legitimate reasons either.
Finally, if you're paying cash, drugstores may, and will, legally dispense the entire quantity on a prescription for a CIII - CV med if requested. People purchasing in bulk for the purpose of distribution wouldn't use their insurance since they'd be typically limited to a 30-day supply.