For the answer to the question above,
Classifying sins is a fairly subjective task, but if we were to go by the famous "seven deadly sins", then her two greatest sins are greed and wrath.
The question of whether Mrs. Walker deserved this fate is uncertain. Does anyone deserved to be killed by the Devil, and have their heart and liver tied up in an apron? It might be better to ask if her fate is surprising, considering the way she lived her life.
the heart and liver have many and mixed meanings, and the exact one intended here is not explicitly stated, if in fact there was any intended meaning as opposed to Irving just attempting to shock his audience. The heart symbolizes emotion, the life force, and love, while the symbolism of the liver is somewhat more obscure, but is often tied to similar qualities, and its functional role in the body is purification. We might interpret that Scratch left these items behind either because they were offensive to him, being associated with love and purity.