What food allergies does your Father have? I would call Delta and see about requesting a Special Meal perhaps an Asian Vegetarian Meal/ Hindu Meal depending on the allergies.

Also it helps to bring your own food with you as well just in case there is an allergen in the food. In the Delta Magazine it states"We cannot guarantee that our products are free from allergens and that the items are prepared in a facility that has Dairy and Nuts". I have heard Delta make an announcement when there was someone with a severe peanut allergy asking passengers not to consume any items with nuts and they did not serve any snacks containing nuts.

I was happy that Delta at least cares to help the passenger with the nut allergy but unfortunately there are still risks.

Good luck and I wish you all a safe trip!