What is BEST for the student?

A student recently  removed from the home due to abuse and neglect may come to school traumatized and under stress. The student may not perform at school as a result of the recent trauma. Trying to make the best decision for the student is so very difficult. It keeps me up at night and wakes me in the morning. It may be in the best interest to retain the student, causing additional esteem or confidence issues. How does a teacher truly know what is best for a traumatized student?