Try reading it backwards and you'll get "Mommy's Treasure".
It's something Maki's mother tought her when she was alone, so when she spelled her mother would be always near.
Did you noticed how much information Tamaki has about demons? Of course she knows a lot about them, she was the very first main female character from Shin Megami Tensei games, at Super Famicom!
She was transfered from her old school (Karukozaka High School) after the incidents at Shin Megami Tensei - If..., in that game her school was sucked into a void and emerges at Makai, a world of demons.