Final answer:
The social worker should prioritize the girl's safety by advising the mother to seek immediate help. They should gather more information about the girl's history and suggest professional support. Additionally, they can provide resources for ongoing support and treatment.
Step-by-step explanation:
The social worker should prioritize the immediate safety of the girl. They should advise the mother to call emergency services or take the girl to the nearest emergency room. If there are immediate concerns for self-harm or harm to others, it is crucial to involve professionals who can assess the situation and provide the necessary support.
Once the girl's immediate safety is ensured, the social worker should gather more information about the girl's history of self-harming behavior and mental health. They can provide guidance to the mother on seeking professional help, such as contacting a mental health professional, therapist, or counselor who specializes in working with adolescents.
The social worker may also consider suggesting additional resources and support services, such as crisis hotlines, support groups, or community mental health centers, to assist both the girl and her mother in finding ongoing support and treatment.