Is Ma helping or hurting?

For my blog topic this week I would like to discuss Ma.
In class we have established that Ma is the hero of this novel and her mission is to keep the family together. But like in every story, the hero is forced to endure daring trials that test their spirit and dedication to their mission. In the beginning of the novel, Ma is calm, collected and the center of spirit in the family. But as time goes on, Ma is hit by many trials throughout the trip from Oklahoma to California. The first test comes with the loss of Grandpa. His sudden loss starts the breaking apart of the family. After his loss, Grandma dies next. The sudden loss of her husband seems to be too much for her to take and she starts showing signs that are similar to that of Alzheimer's disease. Grandma starts speaking randomly to no one in particular and the family assumes that she believes she is speaking with Grandpa. When Grandma finally dies on the mattress, Ma's strength is once again tested as there is another loss in the family and Ma feels her family is falling apart. The next to break up the family is the Wilson's. Though they were not biologically part of the family, they had been through enough with the Joad's that Ma saw them as part of the family. At the same time as the Wilson's leave, Noah, Ma's oldest son, decides he needs to break away from the family as well. Ma's spirit keeps being torn apart as each part of the family leaves. Throughout these events, we can see Ma's determination and frustration when anyone talks about splitting up the family, even if it is only temporarily. The best example of this is when the Wilson's car has a messed up rod and the family tries to decide what is the best way to fix it. When the decision is almost made to leave Tom and Jim Casey behind to fix the car, Ma threatens physical violence if they were to leave anyone behind. Her calming nature is shattered by the loss of the family and it is causing her character to unravel.

My question is, is there a possibility that Ma could cause the family to break up even more? By keeping such tight reigns on her family, is she going to hold them to tightly that they slip through her fingers like sand?