Starting with the 1861 census (just to confirm ages etc)
Reference RG09, Piece 9, Folio 52, Page 4
13 Radnor Place, Paddington
Drury, James S Head M 39 M D London MRGP Ery b Shrewsbury, Shropshire
Drury, Sophia L Wife F 32 b London
Drury, Caroline F Mother Widow F 61 b London
Drury, Mary F Daughter F 16 months b Paddington
Drury, Infant Son M 1 week b Paddington
+ 4 servants
So, Mary was born 1859, possibly December?
Then 1871 census
Reference RG10, 22, 44, 41
Radnor Place, Paddington
Drury, Sophia Head Widow F 42 b Chatham Place
Drury, Mary Frances Daughter F 11 b Radnor Place, Paddington
Drury, Isabella Maud Daughter F 8 b Radnor Place, Paddington
Drury, Emily Daughter F 7 b Radnor Place, Paddington
+ 11 Scholars, Governess, Housekeeper, Servant & Visitor
Sophia is still a widow in 1881:
Reference RG11, 17, 25, 2
13 Radnor Place, Paddington
Drury, Sophia Head Widow F 57 Schoolmistress b Middlesex, London
Drury, Mary F Daughter F 21 b Paddington
Drury, Emily Daughter F 17 b Paddington
+ 7 scholars, some visitors and servants
(N.B. FindMyPast transcription has apparently missed the daughters and some others)