Without the "following locations..." list it's hard to tell what applies. At any rate, it's a 240V application so it exceed the "150v or less" requirement.
Given what zach said, I'm guessing outdoor outlets follow the same general methodology as do indoor units... anything X feet or less from a wet location gets one. Everything else is protected by the circuit breaker.
What are the latest revisions on arc fault interrupters? At one time they were the up-and-coming safety thing to have. Haven't heard much about them in a couple of years, though.
Brad
Here are the locations:
Bathrooms
Kitchens
Rooftops
Outdoors
Sinks — where receptacles are installed within 6 ft from the top inside edge of the bowl of the sink
Indoor wet locations
Locker rooms with associated showering facilities
Garages, service bays, and similar areas other than vehicle exhibition halls and showrooms
Crawl spaces — at or below grade level
Unfinished portions or areas of the basement not intended as habitable rooms
it's all outdoor receptacles, and as Nick1911 noted, and I bolded, the code is 150 VAC to ground, so two 120VAC legs count. Indeed, that "volts to ground" is the change they made in 2017, very probably to cover electric cars and the like.
I saw mention of the Arc Fault Circuit Interrupter Mike mentioned, but didn't feel like running it down last night, so I'm glad he mentioned it.
Functionally speaking I didn't actually see a GFCI plug that size on a quick lap of the internet, so you will probably need to just go the GFCI breaker route. There are prewired "Spa" 50A sub panels for about $100, or you can grab the right breaker to put in the main panel.
Are you adding a receptacle to an existing circuit, or adding a whole new circuit?
Also, how big is the service coming into your father-in-law's house? Is it going to end up if he comes home and plugs the car in, while the stove and water heater are running the whole house trips?