Technically, to gain early entry she will have to be registered in the room with you and by Disney standards, everyone in the room has to have the same package. If you want her to have early entry with you for the 6 days she is with you, I would recommend considering spending the additional $80 to have her bumped from a 6 day ticket to a 10 day ticket and registering her as a guest in your room.
There are many people who are staying on property and meet others in the parks who are not and those guests are not entitled to the ETPE. Basically, this is the situation for your mom as she is not on the room reservation.
I would also be concerned that she would not have access to your room without one of you being with her since, if I'm understanding correctly, she is not on your room reservation.