A 52-year-old male from Delhi presents to the emergency department with tremor, diaphoresis, and agitation. He reports consuming 8–10 pegs of whisky daily for the past 15 years. His last drink was 18 hours ago. Vital signs: BP 148/92 mmHg, HR 110 bpm, RR 20/min, temperature 37.8°C. Blood glucose 110 mg/dL, serum sodium 138 mEq/L. He is oriented to person and place but not time. What is the most appropriate immediate pharmacological intervention?