The thing is, she may have lived even longer if her boy Walt hadn't bought a death trap of a house for her.
Rumor has it that she complained several times about a faulty gas leak in the home, but no one fixed it adequately and she met her fate by asphyxiating on carbon monoxide. We all know Walt may have had an affinity for gas chambers, but despite this inclination he was devastated about his mother's passing, and now we have to endure dead mothers in cartoon form for all eternity.
That her death was the impetus for the startling run of missing mom movies isn't at all guaranteed, but that's not the point. Those movies still exist, and they came at a time when Disney was doing some of his most influential work. The film that bought Flora that house, Snow White and the Seven Dwarfs, was the first American feature-length animated film ever. No mom there, unless you count the wicked stepmother.
How shitty were things at home that living with her was the better option?
Two others that were in production at the time of her death, Pinocchio and Bambi, feature no mom and a murdered mom, respectively. So, I suppose it's just as possible that he secretly wanted his mom dead and that desire was coming through in his work at the time.
Whatever the case, this period kicked off an impressive run of animated feature films from Disney, culminating with the classic Cinderella, about a young girl whose mom is already dead before the cameras start rolling (so to speak).