The family emigrated to the USA when Abraham was a young child, and for a few years, they lived inside the Statue of Liberty, along with their sons, until the head of it was filled with too much garbage.
While in the US, she and Orville had a sixth child, Bill Simpson, who grew to become a Communist. Around the time of the Second World War, their final son Chet, was born, and would grow to run an unsuccessful shrimp company.
Later, the family would move to Springfield, USA, the town in which the show is set.
Although Yuma's death has never been mentioned, she presumably died before Bart, Lisa or Maggie were born.