Complex sentence: Her paternal grandparents were Ranulf de Gernon and Maud of Gloucester, the granddaughter of King Henry I of England, and her maternal grandparents were Simon III de Montfort and Mahaut.
Split into simpler sentences: Her paternal grandparents were Ranulf de Gernon and Maud of Gloucester, the granddaughter of King Henry I of England. Her maternal grandparents were Simon III de Montfort and Mahaut.