Dandruff with dry hair is often due to scalp irritation and lack of moisture. Try using a mild anti-dandruff shampoo two to three times a week and avoid very hot water while washing your hair. You can gently apply coconut or almond oil to the scalp before washing to improve dryness. Keep your scalp clean, avoid harsh hair products, and manage stress as it can worsen dandruff. If it does not improve, consider consulting a doctor for proper treatment.