If you don't find her in the SSDI, then I suggest you look at Jacksonville City Directories for the 1970, 60, and 50s until you find her, which should lead you to her husbands name, unless he died a great number of years before her. And it will narrow down the date of her death. Many City directories list the age of the people in the household. which could give you an approximate date of birth, and a guess-timate at when they married. Failing at else, I'd try deed records, Wills for any Pentecoast in the county.