No way! It is your birth, you should be allowed to have who you want in the room. You get the make the decision on who should be in there. You can request with the hospital staff that no one other than your husband be present at the birth (other than hospital staff) and they will respect that by keeping your mom out.
My doctor noticed that whenever my mom came into the room, I got agitated. He asked her to leave. She got to come in afterwards.
The good thing about babies is we get to take them home with us! Your mom will have plenty of time to bond and get to know your baby later. Enjoy your birth.