Welcome, Shirley! That source citation could be incorrect. It's certainly incomplete. The only record I found in the US Social Security Death Index is for a George Burrowes who died in Florida in 1964. If you have his death certificate, that's the one to trust. Inaccurate information should be removed from the profile.
Here's a citation that might better apply to your grandfather:
"Florida Death Index, 1877-1998," database, FamilySearch (https://familysearch.org/ark:/61903/1:1:VV6F-ZFK : 25 December 2014), George Tillman Burroughs, Mar 1959; from "Florida Death Index, 1877-1998," index, Ancestry (www.ancestry.com : 2004); citing vol. 2044, certificate number 11727, Florida Department of Health, Office of Vital Records, Jacksonville.
I was about to cite his FindaGrave memorial, but I think you created it.
Please let us know if you need help finding any other sources or information!
Edit to add: That SSN belonged to a Nelda Cheney, 1911-1987.
Edit to add further: Mrs Cheney was probably George's widow.
Find A Grave, database and images (https://www.findagrave.com : accessed 9 May 2019), memorial page for Nelda Burroughs Cheney (27 Sep 1911–17 Jun 1987), Find A Grave Memorial no. 176305690, citing Memorial Park Cemetery, Saint Petersburg, Pinellas County, Florida, USA ; Maintained by Dawn (contributor 49172547).
Yep, Nelda Cheney was Alverna Chadwell's sister:
"United States, GenealogyBank Obituaries, 1980-2014," database with images, FamilySearch (https://familysearch.org/ark:/61903/1:1:QVSB-PMR7 : accessed 9 May 2019), Nelda M Cheney, SouthEast, Florida, United States, 19 Jun 1987; from "Recent Newspaper Obituaries (1977 - Today)," database, GenealogyBank.com (http://www.genealogybank.com : 2014); citing St. Petersburg Times, born-digital text.