I'm giving you two ways to control her - a geas whose command word is engraved in an ancient language on the lid of her coffin, and three ancient Seals of the Dead God, one of which is hung around her neck on a breakable necklace. I pity the poor fool who tries to take away this pagan emblem from her.

I should mention, pronunciation is very important for the geas to work.

Glad you like my Dairy flaw. 

I'm figuring the Maw may have had a rat problem before she showed up.