Complex sentence: CR Balakrishnan Nambiar assumed leadership of the movement, with his sister, CR Devaki Amma becoming one of the early organizers of Mahilasangam, an associate organization of the Congress.
Split into simpler sentences: CR Balakrishnan Nambiar assumed leadership of the movement. His sister, CR Devaki Amma became one of the early organisers of Mahilasangam, an associate organization of the Congress.