Complex sentence: "Mother" Stagg and members of the church were active in humanitarian relief work, distributing food and medicine, and performing welfare activities for displaced persons, fugitives from the Japanese (Chinese business and community leaders), and resistance fighters.
Split into simpler sentences: Mother Stagg and members of the church were active in humanitarian relief work. Their welfare activities also extended into helping displaced persons, fugitives from the Japanese (Chinese business and community leaders), and resistance fighters.