What could the us government have done to improve the economy in european nations before the great depression

They could have decreased protectionism. Protectionism means that they limited free trade between nations and restricted trade of foreign goods. Protectionism is widely accepted as maybe the biggest reason for the development of the Great Depression and thus if the US had decreased it, it most likely would not have happened at all.

d: their own individual powers within the new goverment

its main object was the establishment of "settlement houses" in poor urban areas, in which volunteer middle-class "settlement workers" would live, hoping to share knowledge and culture with, and alleviate the poverty of, their low-income neighbors.