With Jones being so common, SSDI might be a bit much to plow through. There are 80 Lula Jones just in TX Dth Idx, didn't even look at SSDI.
Try Kendall Co, TX GenWeb site, some GenWeb counties are putting their cemeteries online. Also, post a query on that site, and the GenForum site for Kendall Co, TX, too. The more places you can post queries the better your chances of someone seeing it that can help you. Be sure and use 4 digits for years, is that 60 in your query, 1860 or 1960? Once you find his death date, be sure to obtain a copy of his death certificate, it should have the names and birth locations of his parents.