From what I know, a visit visa can be extended for six months on the payment of QR 200 per month of extension. As such an extension should not be an issue in your wife's case. You can extend for another month (7th month) on the presentation of a confirmed ticket and on the approval of the captain. Should there be an issue on the extension, the captain will help your wife get an extension on the basis of the doctor's certificate.
As per my experience, all captains are very cooperative, understanding and helpful people.