Thanks for posting that, Brent.
I looked her up on wikipedia and she had a heart attack, which is probably good in the sense that she was 82, able to do a television show eight days before her death, and most likely she wasn't dealing with any long term illness. Good for her, she seemed to be having fun and Groucho was as sharp as ever. I'm glad she got to work with Groucho in the end, they made a great team.
Margaret Dumont, interestingly enough, was born on the same day as Bela Lugosi.