They would have all been extinct without her rituals. There was NO other way. The end. The planet would have been torn asunder were it not for Seren's rituals to quell Mah.
Also, I'm pretty sure if Seren did decided to drain all Mah's powers into the Mahjarrat, she would have required that special energy-pillar ritual marker that I'm pretty sure only Mah could make, which might also explain why Zaros never took all the Mahjarrat back to Freneskae during the Zarosian empire era when he has the chance to finish Mah off.
Lastly, is it so bad to care about your mother? To want to save her, despite all your other family members giving up? At least Seren wasn't some spoiled kid, thinking they were ready to face on the world, while letting their mom rot sick in some retirement home.
I submissively obey Lady Seren's every whim and relish every waking moment willingly serving her. She is my mistress and I am nothing without her. I am without thought, self-awareness, and being without her. She is my everything.