If so, you might suggest that your mother meet with the principal and vice principal to find out what the school administration is like and get acquainted with how things are handled in Lanier.
She can also go to the AISD web site and the TEA and see what the stats are for the school. The comments on the link you provided are at least a couple of years old, so things could have changed.
AISD - http://www.austinisd.org/schools/website.phtml?id=020
Lanier Health Sciences - http://www.austinisd.org/schools/website.phtml?id=121
TEA - http://www.tea.state.tx.us/index.html
You may not like my answer. Parents are protective for a reason. Take her to the school and show her around, meet the faculty and principal. Have her check out the school online: http://www.SchoolMatters.com. The thing to remember is she loves you and wants what is best for YOU. Try to be more patient with her, and remember she is older and wiser and she only has your best interest at heart. I often disagreed with my mother, but the older I got the more I realized she was right more often than I thought as a teen. Hang in there!
With age comes wisdom....