There are three types of joint ownership recognized in Missouri. Whether or not the surviving spouse has the absolute right to sell the home (without the necessity of probate) will depend largely on which type of joint ownership is listed on the deed. The deed will need to be examined by an attorney to answer your question.
Even if the joint ownership is such that the title passes to the wife without probate, then a new deed should still be filed with the Recorder of Deeds in Jackson County to record the transfer to the survivor. This is advisable, though not legally necessary.