Discuss the significance of this ending of The Gathering of the Old Men.

At the finale of The Gathering of Old Men, Mathu agrees to ride back home with the other black men in Clatoo's truck instead of taking a ride from Candy. Throughout the novel, Mathu and the other men stand up for one another and oppose the plantation owner and the officers in the town, unifying against white supremacy in the novel.
While the ride with Candy would certainly be more comfortable, Mathu chooses instead to ride with the many other men cramped in the back of a truck. He does this as a symbolic act of solidarity, saying that, instead of siding with the white people in power and benefiting himself personally, he chooses to accept the suffering that comes with unifying with the other men of color.

Significantly, this novel ends with the ideology that the author has taken some things out of Marshall and places them into a courtroom in a big city. This makes its ending part a surprising one for the readers, as another depiction shows an image of Lou Dimes and Candy standing as they watch Mathu and his friends drive away in Clatoo’s pick-up. The representation illustrates a new beginning for all of the characters involved with their relationships, and how these relationships are being portray. Candy exemplifies that the next age group of Southern white folks, entrenched to a particular spot and still caught in a really unfashionable manner of thinking. On the other hand, Lou portrays the outside world that deals with a fresh and more free-thinking approach of minimizing how things work.

It's significant that Mathu chooses to ride back in Clatoo's truck with the other black men instead of accepting Candy's offer of a lift back to the quarters. This is an expression of Mathu's growing racial consciousness and sense of solidarity with his fellow black man. In their lengthy stand-off with the official—and unofficial—forces of white power, Mathu and the other men have at long last learned to stand tall, no longer feeling that they must bow down before the white man at every opportunity.
The men have taken a brave stand and emerged from their struggle stronger and wiser than before. They've developed an unbreakable sense of camaraderie that will bind them close together for the rest of their lives. As the men can now stand on their own two feet, they have no further need of the kind of well-meaning assistance offered by sympathetic white folk such as Candy. Hence the great significance in Mathu's turning down her offer of a lift.