Was this a beneficiary deed as opposed to the more typical joint tenancy deed? If so the date of inheritance would be Mom's DoD with the resulting step up of basis and title should pass without having to go through probate.
With nothing more to go on than what you've posted I'd say TaxGuyBill's response makes a lot of sense. Everybody shares equally in the gain and there's an agreed repayment of the carrying costs by the brother-in-law.
