Only medical expenses are deductible as medical expenses. Costs for room and board, laundry and cleaning and so on, are not deductible.
If he is in a nursing home mainly for medical care, the entire cost is a deductible medical expense.
If he is in an assisted living facility mainly for his own convenience, he can only deduct actual medical expenses, including nursing care. Nursing care does not have to be provided by an actual nurse but must be the kind of service usually provided by a nurse, such as administering medication, or providing assistance with eating, dressing, bathing and so on. Costs for room and board, laundry and cleaning services, etc. are not deductible medical expenses. The facility should provide a breakdown of their costs and what portion of their costs count as nursing care.
If he is in an assisted living facility due to a chronic illness or cognitive impairment, the entire cost of the facility can be deducted as a medical expense if 2 conditions are met:
1. He is chronically ill and can't perform 2 or more activities of daily living without assistance, or has a cognitive impairment and requires constant supervision to prevent him being a danger to himself or others, either of which is certified by a doctor. Activities of daily living are eating, bathing, toileting, dressing, transferring, and continence.
2. His care is provided according to a written care plan developed by a qualified social worker or health care professional that is reviewed at least annually.
Most facilities will have a nurse or social worker on staff who can prepare a written care plan that meets the requirements.
Insurance premiums paid out of pocket, as well as out of pocket medical expenses for medications and co-pays, are also deductible of course.
There is an overall 7.5% "floor" to this deduction so the entire amount won't be deductible, and he must itemize his deductions to get any benefit. Turbotax will do the math for you on this.
