Martha was married to Curt Connors for many years. Martha stuck by her husband, even when he became the terrible creature known as the Lizard. It was later learned that Martha got cancer. In Spider-Man Quality Of Life #4, she died on the operating table. Curt was devastated by the loss of his wife.
Major Story Arcs
The Clone Conspiracy
Martha along with her son Billy were resurrected as clones, with their memories intact by a new Jackal. When the degeneration wave hit, both of them survived it thanks to Curt Connors' serum. The serum however turned them into mindless lizards.
Spider-Man (1990's series)
Martha appeared in Spider-Man the animated series in the episode Night of the Lizard.
She also appears in the Spectacular Spider-man.