Whether or not your house will be livable after a major fire will depend on many factors, and you will need to obtain permission from the Fire Marshall to reenter your home. Burned or unstable wood in the structure will need to be replaced. After a major fire dry wall is left dehydrated and crumbling and will need to be replaced. Given the high temperatures of large fires, most if not all of the home furnishings may be rendered unusable.
Smoke damage will be severe—particles can permeate everything (especially clothing and fabric) and the foul odor is difficult to remove. Even untouched items in storage are at risk. Water from fire hoses may cause further damage to the structure, foundation and furnishings: mold can grow rapidly in wet or damp areas. Ash and soot can stick to floors, walls and furnishings and cause additional damage due to the caustic byproducts present in the burned materials. Expect to need weeks, if not months, to do cleanup and repair before you can bring your family home.