Complex sentence: She played a key role in assuring that women would be on an equal footing with men from the first inception of the Grange movement, feeling that because the family farm included women, then so should the organization that the family would join.
Split into simpler sentences: She played a key role in assuring that women would be on an equal footing with men from the first inception of the Grange movement. She felt that because the family farm included women, then so should the organization that the family would join.