I also recommend AmeriCorps. The NCCC program is an 11 month live in program - young adults, ages 18 and up, dorm at one of 3 campuses. While their they learn to be tutors, disaster responders and more. They then are deployed in teams of 10-12 to different locations in their region to perform service. AmeriCorps NCCC provides a living allowance, meal allowance, uniforms, job training and living skills training, health insurance and upon successful completion of the program, a college scholarship. It is really a great way for a new high school grad with limited options to get a start.
I ran a local AmeriCorps program for years and have seen the transformation that can occur in young adults through this program. There is an application process and it is a year long commitment so she should be sure that this is something she wants to do. Please check out the program - the website is www.americorps.org
Also check out your state's employment department - many offer job training courses that will help prepare her for work. Look into public transportation if she is not familiar with it so that will help her get around and become more independent.
You are doing a good thing by helping her. God Bless.