Hi again, Death Notice for her son Robert Wilfred Ivan B1910 D1942. He is unmarried when he dies and address is 68 Grandborough C(?)owel, South Beach, Durban. Constance is listed as his mother and living at the same address as him. So, in 1942 she is alive and has not remarried. Marriage for sons George and Claude (both in Durban) witness seems to be the brothers.
Timeline: 1906 Marriage in Durban
by 1917 Birth of 3rd son in Vryheid
by 1942 Death of Robert back in Durban.
Not much, hope it helps
Catherine