Ooo. Interesting.
Bats in waking life can be a help and a hurt to mankind. Most species of bat do not suck blood but rather they feast on mosquitoes and other insects that pose a threat to man and his crops. Bats also help pollinate plants and disperse their seeds.
However, throughout history, many cultures associate bats with negative beliefs mostly because they look imposing with their rat-like looks and sharp teeth, are nocturnal, and well, some types of bat do drink blood.
It's a common myth about bats that they will get tangled in people's hair but in truth, they are attracted to the mosquitoes who are attracted to the humans; then, they get entangled in the hair. They aren't trying to attack the humans.
Enough of that and onto how bats relate to this dream. I don't know if this dream woman was just a female in general (and how you feel about womanhood) or if she represents someone in your waking life. This is for you to know.
But the bat represents someone who can be a pest or threat to her. He can be a drain of her energy and most definitely, mess up her self and public image (hair). Another person will try to help get rid of him but he will have left some damage. She will have lost some self-esteem or ruined her public image (bald) at least temporarily (as hair grows back).