Yes that Sarah can be ruled out now I think. As far as I am aware the Deakins all came from Sheffield but Samuel could have married in Derbyshire.
There is something strange about the whole thing. Sarah was 57 in 1871 when she lived with Sam who was then 17 and she doesn't appear in any census after that. She does appear in the 1861 census living on Saville Street as a lodger but Sam isn't living with her then when he would have been about seven years old. Sam is listed as a wood turner in 1871, though he was grinder later on when he married, but the witnesses on his marriage cert (James and Emily Steele), James owned a wood turning business and he and Emily lived on the same street as Sam and Selina (my grandparents) when they got married, which was Broad Street.
There are these connections but still I can't find anything, so frustrating :)
I have a Sarah Elizabeth Deakin in my tree born Sheffield 1863, daughter of Frederick Deakin and Fanny Pickworth. She married William Moore in Sheffield in 1883. Their children were Emily b.1884, Sarah Elizabeth b.1887 and James Frederick b.1889. William and Sarah Elizabeth Moore are buried together at City Road.
I think this may rule out your Sarah marrying this William Moore in 1883.