why is ma scared of california?

Ma is just trying to keep her family together. California is the unknown. The Joads, like most families, are being pushed off their land. They have nothing left. In California they will be fruit picking drones working for big business rather than themselves. I think Ma is apprehensive about the promises made from the pamphlets about California that are scattered everywhere. Still Ma's priority is keeping her family intact. They have no money and Tom is just out of prison; she worries something might happen to him. The whole family has needs (from children to grandparents) that Ma worries in this new and often hostile environment.