Alcohol is a depressive, so it would not help his depression. It could interact with his prescribed medications which would also impair his driving if he drank and drove. In order to decrease any chance of a car accident that could injure people, appropriate measures need to be taken.

House rule of no alcohol should be adhered to. Whatever the reason for self medication with alcohol, it is likely to lead to a habit. In order for him to process the loss of his job, his wife, and self esteem, he needs to work through his therapeutic plan.

It has to be a firm approach regarding the alcohol, but it needs to be done. Mention acknowledgement of his difficult situation(grieving aforementioned losses), but he needs to work it out without alcohol.

You know your son better than I, so tailor my suggestions based on your judgement. You could also try Alanon for support if you feel it is required. Take care.