Although I have not found a grave for Isabella which could have helped with more detail, I did find that she had married a Solomon, as can be seen by the mortgage she took out in 1900. Unfortunately the records for this are held in Cape Town and would require you to obtain the services of a researcher who would then have to copy them out by hand as no records in Cape Town can be photographed.
DEPOT KAB
SOURCE DOC
TYPE LEER
VOLUME_NO 4/1/725
SYSTEM 02
REFERENCE 2607
PART 1
DESCRIPTION MORTGAGE BOND. ISABELLA MARION ROCHEFORD MCGIBBON SOLOMON, BORN
HEPBURN.
STARTING 19000000
ENDING 19000000
Hope this helps