Buzios’ main nightlife area is basically a couple streets w bars and restaurants. Decent food options. Don’t remember where exactly I ate. Just take a walk through and see what looks good on the dinner guests’ plates (lots of outdoor spots). And be sure to try the moqueca (fish stew). I don’t like stews but I loved that dish.
Also rent a dune buggy to visit all the beaches. It’s by far the best and most fun option to get around.