How does the refusal of the court to grant custody of Huck to the Widow of Douglas and Judge Thatcher reflect on society?

This happens in Chapter 5.

I think you can see it in a couple of ways.  First, if you want to, you can say that this is a society that believes in the importance of family and in the idea of giving second chances.  The new judge believes Pap when he says he's going to turn over a new leaf.  And he thinks that it is best no to break a family up.

Second, if you are less charitable, you can say it is a society where the the rights of the weak are ignored and the rights of the strong are upheld.  In this case, a parent is being given the right to abuse his child, who is too weak physcially and socially to stop the abuse.  You could even relate this to slavery and say that society is treating Huck like it will treat Jim later -- as people with no rights who can be abused by those who "own" them.