Is it permissible to assist a family that is not religiously observant, or is it more deserving to assist a family that is committed to religion and prayer?

It is permissible to help family members who are not religiously observant, as long as it is not known that the aid will be used for something forbidden. This is similar to how the Prophet, peace and blessings be upon him, permitted Asma bint Abi Bakr to maintain ties with her polytheist mother, and as the Quran indicated the feeding of a captive, even if he was a polytheist. However, it is better to help those who are religiously observant, as charity is more befitting for the people of piety and knowledge.