Support when extreme
Stress
How do I support a person facing a stressful situation?
Suppose the symptoms are medium to high in severity. In that case, one must wait and prioritize 'restoration of mental health'. Even if one decides to go ahead and take the job, appear for the exam, etc., while having symptoms, it may increase stress and worsen the situation. Recovery time tends to increase with unsuccessful attempts.
Crisis
How do I support a person in crisis?
Contact the treating mental health professional and follow their advice.
Meanwhile, understand:
A violent person feels insecure. Try to empathize with their insecurity and the danger the person is experiencing. Acknowledge it (don't advise) for the time being if possible. Try to give the person a sense of security.
Suicidal: Genuinely listen to their feelings. Assure the person that you are listening. Try to keep the person engaged in talking. Don't advise or ask questions. Keep dangerous things out of reach.