B737 flight crew reported hydraulic failure in cruise resulting in a return to departure airport.

Narrative

I was Captain of Flight XXX; ZZZ-ZZZ1. Normal takeoff and climb to FL340. At XA40Z the #2 engine driven hydraulic pump low pressure light illuminated. Hydraulic pressure system B slowly dropped to a very low indication with the system B pressure showing 2;980 PSI. The QRH (Quick Reference Handbook) was ran. Dispatch was contacted via frequency and a patch with Maintenance Control was initiated. B system quantity was showing 106 with pressure holding around 3;000 PSI. It was decided that the indicator failed and we (Dispatch; Maintenance Control; and Flight Crew) decided that it was fine to continue to ZZZ1. The FO (First Officer) and I decided to closely monitor the hydraulic systems as we continued. Approximately 6 to 8 minutes later; we saw the B system pressure drop to 100 psi with a zero quantity indicated. We ran the Hydraulic System B failure checklist in the QRH; contacted Dispatch and Maintenance Control. We decided to return to ZZZ. We requested priority handling and returned to ZZZ with an uneventful landing on RWY XXL per the QRH.