That aside, I'm not sure I understood your prediction. From my reading, it seems as though you are interested in how environmental factors influence development in children. There actually has been lots of research on this. You mention that you want to examine three risk factors; maternal education, maternal depression, and socio-economic status. However, these aren't necessarily environmental factors, especially if you focus on the mother. You then switch gears and mention family financial stability.
I'm confused as to what your focus is. Why not create a study in which you look at family financial stability, emotional support, access to resources, etc., and their relationship with child mental development (by which you mean what, exactly?).
These ideas are still a bit broad and not necessarily testable. Students need a testable hypothesis that can be examined in a single study.
The potential study I mentioned above could work. How do you feel about that idea?
Let me know if we need to meet about this. I'm concerned this idea isn't concrete enough to start working on the draft.
I look forward to your response.
-Adrian