I see from 1881 she was born 1854 Scotland, husband not present, a marine surgeon.
Here she is in 1901:
RG13/47 fol.47 p.40 110 Brackenbury Rd, Hammersmith
Thomas Plews head mar 22 Carman Scotland
Janette " wife " 20 Shirt Tie Maker Islington
Thomas " son 4 mths Hammersmith
Isabella " mother mar 47 Scotland
looking for 1891 now
Barbara