California Grill is at the Contemporary, next to Magic Kingdom. While you certainly could take the Skyliner to Epcot and walk the .6 miles to the monorail station from International Gateway, then take one monorail to the TTC and transfer to another monorail on the resort line, your best bet is probably to take the bus from Caribbean Beach to Magic Kingdom and walk over to the Contemporary via the dedicated walking path. Park buses run until the park is fully empty, which could be even a couple of hours after advertised closing time, so you'll likely be able to get back via bus from Magic Kingdom to Caribbean Beach without issue.