Teacher salary schedules are often based on # of units after undergrad. She can look for a school where she will get her credential in 4 years and start teaching right away but, in general, she will be working at a lower salary. Alternatively, she can get her bachelors degree in whatever subject she wants and then get a teaching credential and/or masters at another school.
After undergrad, she will be seen as financially independent, regardless of whether you claimed her on your taxes the year before. You can find credential/masters programs that are subsidized (free) if you pay back by working for certain districts.
Many credential/masters programs are two years - a student receives the credential the first year and works as a teacher while completing a masters (evening) the second year. Others, utilize summer school and a student receives a credential and masters in one calendar year. Look at teacher salary schedules in your area to see how the salaries change based on units after BA/BS and what types of bonuses are offered for advanced degrees (masters, EdD, etc).
Why would it be OOS?