Is it Legal for my mother to claim me and my newborn daughter on her taxes,

I turned 19 on october 25th, and my daughter was born towards late november,

my mom says she can claim me because i lived with her more than half the year,

(understandable)

but why my daughter?

I moved out of my moms house into an appartment with my girlfriend in the begining of november.

I am the head of the household of the appartment.