By the time the novel ends, you've spent so much time with the folks out at Marshall that you can probably see "the bushes and weeds," that grow "so tall that the road […] seems no wider than a king-sized bedsheet," as clearly as if they were right outside your own window (8.3). Maybe you're even craving a few of those pecans that characters keep mentioning.
That's why it might come as a surprise to you that, in the final chapter, Gaines takes us out of Marshall and puts us inside a courtroom in a big city. And after we've spent so much time with so many of the old men (and we haven't even heard from all of them), it also might come as a surprise to you that we end with an image of Lou Dimes and Candy standing together as they watch Mathu and his pals drive away in Clatoo's pick-up
Remember: Gaines's novel is all about the characters, their relationships, and what those characters and those relationships represent. Candy and Lou are a great example. Candy embodies that next generation of Southern white folks, rooted to a single spot and still stuck in a really old-fashioned way of thinking. Lou, meanwhile, represents the world outside of all of that, even a way out of all of that—a new and more enlightened way of understanding how things work.
Oh, and it's also worth remembering that they had a nasty fight not too long before we see them again. The fact that they're holding hands signifies that what's gone down at Marshall has created the possibility of the worldview that Candy represents changing for the better, which is Gaines's way of telling us that a better and brighter future is possible. Heck, we even learn that Gil is sitting with his family watching the trial, which tells us that even Fix has come around to at least kind of accepting the fact that his son doesn't think the way he does.
So how do Mathu and his pals figure into all of this? Well, the ending represents a new start for all of them, too. They've proven that they can take a stand, fight back, and take control of their own lives. That image of all of them driving away together is meant to show us that this whole experience has made an already tightly-knit community come even more closely together. All in all, it's a pretty happy ending—but it's still one that's designed to make us think.