Ford focus vs Ford Fiesta vs Fusion hybrid

I'm pretty sure they're all towable, it's just a matter of which you prefer. The hybrid will be the heaviest and may be pushing it for your class C. I have a Fiesta ST (not towable) that's pretty minimal on space, but is enough for my needs and it's a blast to drive. The Fiesta ST and Focus ST are six speed manuals and can't be towed.

The main difference in the models you're looking at will be space and weight. You'll need to see which size is a best fit and verify that your C can pull it.