The fact that Frances thinks she is headed south instead of her intended north has two main implications. The first is a play on the expression "gone south," meaning that something has gone astray. Which is exactly what happens to Frances's dreams in this chapter. Her vision of unity with Janice and Jarvis is shattered by the cold reality that she was deluding herself all along. But this must not come as a total surprise to her. She has a distinct sense of foreboding on the bus, somehow knowing that the direction in which they travel acts as a kind of storm cloud up ahead. The second implication of the southern direction is a mere geometrical analogy, as she is headed down instead of up. Her attempts to unify with the married couple turn out to be a regression into childhood whining and general hysteria. And here, all along Frances thought that being a member of the wedding signified a great advancement on her part. On the contrary, it was a type of apex of childish fantasy. But with this belief shattered, Frances is able to experience catharsis, as she does on the bus ride home. It is only after such a stark realization that the maturity that Frances has longed for can finally come to fruition.
The analogy of the bridge game holds some interesting insights into why the wedding was a failure. The bridge game failed because John Henry saw the inherent sexual connection between the jacks and the queens. So he took them out of the deck to give them their privacy, almost. Hence, the game failed because it lacked sex. This is what is wrong with Frances take on the wedding. She does not understand that sex is one of the most important aspects in the unity between a man and woman. Without this key piece of information, she is clueless to explain why a third party is not welcome. However, deep down she does know why the wedding was not a success, or she never would have made the connection to the bridge game.
John Henry's death is handled in the same brisk manner as the presence of Janis and Jarvis. We are just given a few skimming reflections on the event and left to wonder why it is not given more importance. The reason why is because John Henry's role as Frances's foil has exhausted its use. In the story, he functions as a youthful, levelheaded counterbalance to Frances's hysteria and attempts at adulthood. He is merely an object, much in the same way that Jarvis is an almost imaginary figure onto which Frances' can place her fantasies. John Henry has to disappear in the end because Frances finally begins to grow up, and experiences "the changes," whatever they may be. Berenice's last words to him before he falls gravely ill are "Run along for I don't have the patience to fool with you." It is as if she is really speaking to Frances, saying she's not going to put up with her shenanigans any more and that she had better grow up. When he's dead, Frances remembers his ghost in a way parallel to the way she remembered the ghost of her younger self, or "the old Frankie," in Part Two.
"The changes" McCullers mentions could be any number of things: Frances's newfound friendship, her lack of interest in the freak house, and her maturity. But most fundamentally, the word "change" probably suggests that she has finally had her first period. The expression brings to mind the expression "the change of life," often used to describe women going through menopause. So the word has a certain resonance to it that suggests that Frances has finally entered her childbearing years. The bell that rings in the last sentence is like the clock that announces that her biological clock has started to tick forward.