Naturally, my first instinct was that I would seek medical attention for Roderick and Madeline because they are so gravely ill. Yet, I'm not sure how plausible this really is because there weren't extensive psychological treatments available to them. As I was thinking about this I also realized that I was still looking at this from an outsiders perspective.
When you delve into the story, the narrator and Roderick are very good friends and it may have been hard for the narrator to cope with the fact that his longtime friend was sick and had many psychological issues. With this natural tendency to dismiss things that we don't like, the narrator could have just passed his sickness off as something that wasn't as great as it was. So how can a person help their friend when they don't accept the fact that he has an illness?
So to answer this question, I would have to find someone that would be able to help them so that they don't go crazy and bury someone/get buried alive.
If I were an active participant in the story, I probably would have tried to figure out if Madeline were truly dead. Even though she would fall into death like trances, her heart would still be beating. Even if it just beats slowly, it still beats and that makes her still alive.