There are several solutions.
1. Move the NAS to where your switch and router are located, connect the NAS to the switch, and convert the PC to wireless.
2. Buy a couple of powerline adapters that can send ethernet over the house AC wiring. Connect one to the switch and plug the other one into an AC outlet in your home office. If you get a model with two gig ports, you can connect the PC and the NAS directly to the powerline adapter. The advertised speed on the box is exaggerated, but it's not bad.
3. If you have cable outlets in the office and near to the switch, you can use MoCA adapters to send ethernet over coax. This is basically the same concept as #2 except using coax instead of electrical wiring to transport the ethernet.
4. An all Ruckus solution would be to add an R510 to the wired network (or replace one of the R320 APs with an R510). Place the H510 in the office and mesh it to the R510. Use the switch ports on the H510 to connect the NAS and PC.
Lastly, it might be worthwhile to ask a top-notch cable installer to take a look. The really good ones can many times figure out how to get a data cable to an impossible location.