The Fall of the House of Usher question?

Ok, so, when the Narrator and Roderick saw Madeline in the doorway after she supposedly came out of the coffin, was that their imaginations playing tricks on them? Because there was no way she could have gotten out of a coffin that was bolted down. She was sick and she hadnt had water for several days. It was windy that night, and the sounds they were hearing were probably from the wind knocking things over in the house, and the house itself creaking. And Rodericks insanity rubbed off on the Narrator, so were they both just imagining Madeline in the doorway? And did Roderick have a heart attack and die from this imagination?