According to the notification of her death, she died on the 21st of February 1940. See "South Africa, Cape Province, Civil Deaths, 1895-1972," database with images, FamilySearch (https://familysearch.org/ark:/61903/3:1:9Q97-Y3Q3-Z1B?cc=1779109&wc=Q81G-HQC%3A139965101%2C142592001 : 24 June 2016), 1940 > Somerset West > image 64 of 320; National Archives, Pretoria.
Blanche Mavis van der Spuy (Burton) is buried in the The Strand Cemetery at the location displayed on the map below. This GPS information is ONLY available at BillionGraves. Our technology can help you find the gravesite and other family members buried nearby.