Mom raised 11 children and did a spectacular job. Why is it that the children do not help care for Mom back ?

Many women from the 40s and 50s had a very defined roll. They put everything into their families and, very often, sacrificed their own needs. If you are too self-sacrificing with your children, they never learn how to give back and, basically, stay in that child mode well into adulthood. They want the Mom to give, even as they grow older and need help themselves. (I speak from experience.)
You will find that most everyone in this forum has sibs that sit back and do nothing while one person steps up and takes on the complete responsibility.
It is amazing to me how anyone could look away when someone is in need...especially a parent.