Who do I need to speak with concerning my son.

Civil commitment means that he has not agreed to stay for treatment, and that the State is looking for the ability to keep him in the hospital even if he wants to leave.  You do not "have" to appear because he will be given a public defender, and there will be a doctor to testify as to the need for treatment.  If your son lives with you, and you provide a support system for him, you can go to the hearing, and indicate that if he were discharged, you would be able to have him come home to you, and you would provide care.  if the State does conclude that he should be committed, he may be transferred from the facility where he is to a State psychiatric hospital.  Which hospital depends on the location - either Ancora or Trenton, neither of which is a good thing to happen.  You should go to the hearing.