Quote 49
She also realized it was most likely these sodden days at the Hitler Youth that fed his, and subsequently her own, desire for crime. (39.82)
We see this pattern over and over again. The crimes committed against Rudy by Hitler Youth leaders help cause Rudy to commit some crimes of his own.
Quote 50
Liesel Meminger was a criminal. But not because she'd stolen a handful of books through an open window. (54.134)
Here, Death is referring to Liesel's inability to do what she thinks she should – apologize to Ilsa Hermann. In Liesel's code, failure to apologize is a great crime. So, she does apologize to Ilsa in the long run.
Quote 51
[…] Hans Hubermann held his hand out and presented a piece of bread […]. (58.62)
Feeding the Jewish prisoners on their way to Dachau is obviously considered a crime by the Nazi guards. It can also be seen as an act of non-violent resistance to what the Nazis are doing. It might seem like a small thing, but it was big to the Jewish people who saw it as an act of true kindness.