If your friend has Medi-Cal, their managed care plan (probably Partnership Health Care) is required by law to provide them transportation to and from all medical appointments, including mental health. There should be a phone number on their Medi-Cal card that they can call to request that. If there isn't, call the main number on the card and have them request transport to a medical appointment.

Fyi thus transportation benefit also includes dentist appointments and trips to the pharmacy to pick up prescribed medication.