Jim is now freed and he is able to be on his own and huck is going to get adopted by his aunt sally.
I think this has a lot to do with the Huck's relationship with Jim in the novel.
Jim is free and hopefully returning to his family, and Huck has decided that adoption and civilization just isn't for him. They are both ready to journey onward alone and have learned many things together, but they are neither one of them in need of each other's protection any longer.
At first, Jim is just a slave, someone to tease. As they spend more time together, Huck comes to see Jim as a man. Jim helps him, talks to him, shares thoughts and ideas, and even risks a lot for Huck. The transformation takes time, though, as Huck continues to consider his "sin" of stealing a slave. But he finds that Jim is like a father to him--indeed, even better than his own father. This realization leads him to turn away from what "civilization" says is the right thing to do and to choose hell over turning Jim in. Eventually he turns completely away from civilization, which he believes is not at all civil.
