Use well-bred Megatheriums, which gain a powerful insect-slaying buff against the Broodmother and her summoned spiders; Rexes or Therizinosauruses are viable alternatives. Bring a Yutyrannus to maintain its courage roar and optionally Daeodons for healing, while using strong saddles and keeping your support creatures safe. Have the attackers surround and focus the boss, and stay mounted to manage buffs and commands throughout the fight.