Q. We are supposed to trust and have bitachon in Hashem that things will turn out good and not overdo our hishtadlus (efforts). Yet at the same time if someone approaches us for help, we can’t turn them down and tell them Hashem will help you and have faith in Him. Rather we have to do everything possible to help the needy. How then can we ever have a situation of true bitachon, and not do unnecessary hishtadlus, if we always have people that depend on us such as family and we have to do as much as we can for them? Are our own dependants less important than strangers?
 
A. Bitachon, trust and faith in Hashem does not imply that things will turn out necessarily good, or at least not in what we consider good. It means that the results would be good in the eyes of Hashem which ultimately would be the best for us.
Horav Shlomo Miller’s Shlit’a opinion is that your question is complex and requires a more ample space than the one provided in this forum. He suggested first to become familiar with the principles involved and explained in many Musar and Hashkafa seforim, such as Emuna and Bitachon written by the Chazon Ish.
He also mentioned that in regards to close family members such as one’s spouse and children, you also have to consider the liabilities and obligations accepted at the time of marriage, that cannot be absolved by one’s call for bitachon in Hashem.

Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit”a