We see George's widow in 1891 living at 14 Victoria Square, Egham, Surrey:
Ann Knibbs Head Wid 35 Laundress Egham Surrey
Emily Knibbs Daughter 16 General Servant Egham Surrey
William R Knibbs Son 14 Egham Surrey
Annie Knibbs Daughter 12 Scholar Egham Surrey
Charlie Knibbs Son 7 Scholar Egham, Surrey
John Knibbs Son 4 Scholar Egham Surrey
William Bryant Boarder 13 Telegraph Messenger Egham Surrey
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In 1892, Ann married Charles Thomas Mansfield. Sadly he died less than a year later, and it seems that Ann reverted back to using the surname Knibbs.
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In 1901, we see Ann, now twice widowed, living at Egham, Surrey, but am not sure why she reverted to using the surname Knibbs after her 2nd marriage:
Ann Knibbs Head Widow 44 Egham Surrey
George Knibbs Son 17 Groom Domestic Old Windsor Berks
John Knibbs Son 14 General Servant Old Windsor Berks
Louisa Knibbs Daughter 6 Egham Surrey
Edith Knibbs Niece 12 Old Windsor Berks
George Howard Visitor (Single) 46 Carter Egham Surrey

Edith is the daughter of Ann's brother-in-law Edward Knibbs and his wife Frances. Edward died in 1900 and Frances in 1893 leaving Edith an orphan at the age of just ten years of age.
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We see Ann again in 1911 living at Chester Cottages, Blays Lane, Englefield Greem, Surrey:
Ann Knibbs, Head Widow F 60 Laundry Worker Egham Surrey
Emily Knibbs Daughter Single F 36 Laundry Worker Old Windsor Berks
William Knibbs Son Single M 34 Plumber Old Windsor Berks
Louisa Knibbs Daughter Single F 17 Englefield Green Surrey
Albert Knibbs Grandson M 11 Scholar Englefield Green
Agnes Knibbs Granddaughter F 5 Portsmouth Hants
George Howard Boarder M 61 Farm Labourer Englefield Green Surrey

I believe that Albert and Agnes are Emily's children.

Louisa is a bit of a mystery. Should was born too late to be a daughter of Ann's second husband, Charles Mansfield, and would in any case have been baptised as Mansfield rather than Knibbs. She could perhaps be Anns granddaughter, born to Emily, but given that Emily's other chioldren are listed in the census as grandchildren, I somehow doubt it.
I've chosen instead to assume she's Ann's daughter from a spouseless relationship.
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For some reason, Ann's burial record has her as Ann M Knibbs, not Mansfield.