The company deducts the expenses related to the truck because it belongs to it. However, your spouse’s personal use of a company vehicle is a taxable fringe benefit. The amount usually is reported as such on Form W-2. There is nothing for your spouse to deduct…the company deducts the business driving and there’s no deduction for personal commuting.
On Form 1040X, you may file an amended return within a three-year period to claim a refund or correct a mistake made on an original or previously amended return.