In the book the fall of the usher what madeline thinking when she awakens to find herself in a casket?

Well, Madeline is pretty much a zombie at this point, so I don't really think she is thinking much once she wakes up from her death. She leaves her coffin and lunges towards her brother, who may be the one responsible for her death. Maybe she wanted revenge, which is why she took her brother with her to the realm of death.