I've been trying to work out what happened to Carolina Helena Maria Friederichs née von Holst for some time now.
Recently I've been working on the Tourrier branch of the family - Carolina's sister Constantia married a Tourrier, and I'd found that her husband Jean Furcy Tourrier may have been buried in Kensal Green Cemetery.
I sent off a query and hit the jackpot:
Jean Furcy Tourrier was buried in Kensal Green Cemetery in 1867 in grave 20207, square 105, row 10. Also buried in that grave were Constance Tourrier in 1877, Albert Charles Millet in 1878, Alfred Holst Tourrier in 1892, and Caroline Fredericks in 1884.
Constance Tourrier was Jean Furcy Tourrier's wife - baptised as Constantia - with Constance obviously an anglicised version of the name.
Albert Charles Millet was the husband of Ida Sarah Tourrier, one of Jean Furcy and Constantia Tourrier's daughters. I don't know where Ida was buried - she died in 1919, after three of her four children, so perhaps she was buried with at least one of them.
Alfred Holst Tourrier was one of Jean Furcy and Constantia Tourrier's sons. He never married.
Caroline Fredericks was Carolina Helena Maria Friederichs née von Holst. Realising that she might have lived under an anglicised version of her name I searched through the English censuses to see if I could find her. The last time she was listed under the spelling of Friederichs was in the 1851 census. But there she was in the 1871 and 1881 censuses, as Caroline Fredericks. She was noted as widowed, and lived with a servant, or boarded with another family. So she was buried with her sister and some of her sister's family. It suggests to me that her husband, Joachim Friederichs, died overseas, and then she returned to England to live out the rest of her life. I'm glad I finally tracked down where she ended up, and her final resting place.