Sarah and Robert had no children, she being almost 50 when they married.
From: Hugh Casement
Dr Frederick Edmund Hubbard, LRCP, MRCSE, of Diss.
I couldn't find Frederick's birth, but in the 1881 census he was 23, b. Margate, medical student, living with his widowed mother Martha, age 66, who was keeping a boarding house at 33 Dalby Square, Margate.
In The Times I found an announcement of his marriage to Sarah (the service conducted by her brother James), her nickname given as 'Pussie', though in our family she was known as Sadie. That's to say, very little has come down to me: the Browns were a taciturn lot, who didn't keep up with siblings, and in any case my grandfather (Charles' brother) was already in his 50s by the time my mother came along.
I also found Frederick's death at The Cedars in Diss. It seems that Sarah then took in a lodger, young Charles Brown (who may also have taken over the practice), and the following year they found themselves married! She was several years older than her first husband and considerably older than her second.
I haven't found her death; nor could I find a third marriage after 1924.