With that location, they are going to be spending a lot on cabs, for sure.

The Anse Marcel Beach Café/Restaurant, at the other end of the beach from the Riu, is excellent. They can walk the beach to get there. The Jam Rock Café back out on the "main road" is good; local Caribbean food. Ti Bouchon is highly rated although I've never been there when it was open (I go in June). There's also a pizza place on the main road that folks say is good, although I've never eaten there either.