Yes, you can hire a private cab from Port Blair to reach Rangat. Neither you have to look for a return option nor would you have to hire any other public transport as the driver will be accompanying you from Port Blair. You can reach your hotel and go for sightseeing by cab itself. As your driver is a local of the Andaman Islands, he will be able to tell you about the place and takes you to various points of attraction. He can also suggest to you the best places where you can eat.