This is a chain with multiple locations in Alabama, Florida, Georgia, Kentucky, Tennessee, Louisianna, Mississippi, North Carolina, and South Carolina – the Southeast basically. See their website (below) for locations.
Though I can't vouch on how good the food is, Sonny's does their best to accomodate food allergies. They have an allergen PDF on their website that lists which menu items contain which of the top eight food allergens. If you have multiple food allergies, you will have to mix and match to find the best menu items for you, but it is useful nonetheless.
Though cross-contamination may be an issue (check with the location if it is a concern for you) they seem to have a few solid dairy-ingredient-free menu items to choose from.
Unfortunately, this doesn't look like a very vegan-friendly dining spot.