They have sofa beds and two doubles at the Beach club. There are two sizes do sofa bed though so you'd need a larger one, and even that would be a squeeze. Nice big room though. However, I'd go for 2 connecting rooms at a value if they need space as you'd get two bathrooms as well. What they wouldn't get is free dining. Depends how they want to eat of that would be an issue.
Only other option not mentioned would be Fort Wilderness. One double bed, one murph I bed and bunk beds. Not sure what adult would want a bunk though!!!!!