This kind of question invites you to make a connection between the music you enjoy and the themes and images in the story. It's a fun way of finding some universal idea or common feeling, a way to discover that musicians today give voice to the same struggles and emotions that the authors of novels like this one have done.
In Chapter 29 of the novel, the mood is one of intense relief, wonder, and reflection as Scout recounts what happened to her and Jem when they were attacked by Bob Ewell and saved by Boo Radley. The chapter ends on an especially poignant note as Scout sees Mr. Radley clearly for the first time and manages to greet him politely.
So, we're looking for songs that express either the feelings prominent in this chapter (a mixture of relief and sadness at Ewell's death, gratitude for being alive, a release of tension, etc.) or the images or sensations important in the chapter (Atticus suddenly appearing as though he is aging, the costume crushed to a pulp, the feel of cooler ground beneath a tree, and so on).
Below are some suggestions, but you can find many more. I'll start with some Top 40 tunes of the current week, then move on to some older songs.
1. "My House" by Flo Rida. In this song, the singer talks about the comforts and excitement of being in his own home, entertaining guests, and doing whatever he wants. Similarly, Scout feels relieved to be back at home, surrounded by the people she loves most.
2. "One Call Away" by Charlie Puth. Here, the speaker asserts he'll be even better than Superman; he'll be nearby, ready to swoop in and rescue someone. His words could be spoken by Boo. How was Boo just conveniently there, ready to save the children? He's like the speaker of the song: watchful, ready to take care of people, eager to protect them against villains like Ewell.
3. "Across the Universe" by the Beatles. The singers express a serene joy in the idea that, although words and images seem to float by them almost chaotically, they still feel a sense of security and safety. That is, although everything is always changing (like Atticus growing older) things still remain basically the same in one's own little universe (Maycomb, for Scout).
4. "Tomorrow Will Be Kinder" by the Secret Sisters. In this song, the singers express the relief tinged with sadness that comes out of experiencing something dark but having recently put it behind them. Scout probably feels the same way: both haunted by the fact that someone's life has been taken and that she was involved as well as relieved that she's now safely at home, the trial over, the town ready to move on: "trouble haunts my mind," "around me lies a somber scene," "a brighter day is coming my way."