Just looking at what his mother says (and what the narrator says about her) in the book, you can get some ideas.
First of all, she is somewhat ashamed of Rufus being a "jailbird." Second, she is really worried about him. She wonders how she is going to keep him from getting in trouble again. She asks the probation officer how things are going to be any different -- how she will be able to keep Rufus from going bad again. She hopes that his job will help with this because work is a cure for hell-raising, but she's not sure it will.
So to me, the main thing is that she's worried about his future.