We see William in 1871, living at Sussex Place, Bath Road, Upton Cum Chalvery, Buckinghamshire:
William J Knibbs Head Mar 38 Butler Surrey Egham
Eliza Knibbs Wife Mar 40 Middlesex Staines
Elizabeth M Knibbs Daur 5 Scholar Berkshire Windsor
Caroline Knibbs Daur 2 Buckinghamshire Eton
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In 1881, we can see William living and working away, and living at 30 Portsman Sq, London, Middlesex, England:
William J. KNIBBS ? Serv (Head) M Male 48 Egham, Surrey, England Butler
Helen BIERCH Serv U Female 34 Scotland Cook
Maggie MC DONALD Serv U Female 27 Scotland Housemaid
Elsie SMITH Serv U Female 20 Scotland Kitchenmaid

His wife and children living at 26 Bexley St., Clewer, Berkshire, England:
James GOOD Head U Male 25 Clewer, Berkshire, England Carpenter & Joiner
Mary E. GOOD Mother W Female 49 Egham, Surrey, England Housekeeper (Dom)
William GOOD Brother U Male 22 Slough, Buckingham, England Carpenter & Joiner
George GOOD Brother Male 11 Slough, Buckingham, England Scholar
Joseph GOOD Brother Male 10 Clewer, Berkshire, England Scholar
Gustavus GOOD Brother Male 3 Clewer, Berkshire, England Scholar
Helen GOOD Sister Female 14 Clewer, Berkshire, England Apprentice Mantle Maker
Eliza KNIBBS Wife M Female 49 Staines, Middlesex, England
Elizth.N. KNIBBS Daur Female 15 Windsor, Berkshire, England Pupil Teacher
Caroline KNIBBS Daur Female 12 Eton, Buckingham, England Scholar
Emma COOPER Neice U Female 40 Tooting, Surrey, England

I imagine that James Good was a family member of Eliza's - quite possibly an uncle given that he had a neice with the same surname as Eliza living with him.
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In 1891, William was still working and living away from home this time at 13 Palace Gardens, Westminster. The census return for that address doesn't give the name of the head of the household, but it does identify that she was a widow and a Countess Living on Own Means, and born in Jamaica, West Indies:
.........................Head Widow F 50 Countess Living on Own Means Jamaica WI
Martha Ellison Servant Single F 58 Domestic Kirby Lancashire
Christine Fraser Servant Single F 35 Domestic Scotland
Louisa A Staff Servant Single F 25 Domestic Odecombe Somersetshire
Elizabeth Harmeston Servant Single F 27 Domestic Woolsthorpe Lincolnshire
Marion Prentice Servant Single F 23 Domestic Scotland
Mary E Dickenson Servant Single F 27 Domestic Stratford Lancashire
Emma Byford Servant Single F 19 Domestic Sebbe Headingham Essex
Clara Slagg Servant Single F 19 Domestic Odecombe Somersetshire
William J Knibbs Servant Married M 58 Domestic Egham Surrey
Francis J WarrenServant M 22 Domestic London
Sebastian Molyneux Servant M 22 Domestic Bayswater
Richard C Sills Servant M 24 Domestic Stanmore Middlesex
James H Hall Servant M 41 Domestic Bristol Gloucestershire
Anna Hall Servant F 29 Domestic Chobham Surrey
Albert Griffen Servant M 30 Domestic Littleworth Gloucestershire

His wife was living at 11 Chepstow Place, Kensington, London:
Eliza Knibbs Wife Married F 60 Lodging Home Keeper Staines Middlesex
Elizabeth M Knibbs Daughter Single F 25 School Mistress Windsor Berkshire
Susanna M Good Lodger Single F 43 Living On Own Means Fulham London VIEW
Frances Good Lodger Single F 40 Living On Own Means Fulham London VIEW
Elizabeth M Counter Servant Single F 20 General Servant Kenton Devonshire

We can see Eliza in 1901 living on her own so presumable William had died:

Eliza Knibbs 71 Middlesex Staines Surrey Clapham Living On Own Means

Caroline died aged just 14.