A person is consuming alcohol since 10 years is brought to hospital emergency with complains of fearfulness, misrecognition, self talking and seeing snakes and reptiles all around him. Physical dependence is present since last 2 years. He has an intense craving for alcohol and from last 1 year, he is having behavioural changes and experiencing different family and social issue. Sometimes he is said to have few tremors during night. The person is suffering from:March 2013 (b, d, f)