Can my dads gf take over his house after he passes?

Our father has a girlfriend that occasionally stays over, although recently my father tried to get her to leave & wanted to marry my mom , my father went in for a surgery & unexpectedly passed yesterday a week after. She went to his house while my brother & i were gone making funeral arrangements changed the locks has stayed in & the police say I cannot go inside. Although I live their as stated on my id & not on hers. is this right, what can we do?