I found no one called Boult on the IoM in either the 1881 or 1901 census. Nor did I find James Boult in either census. Possibly Sarah was widowed.
Also, per the 1881 census info, Sarah (aged was born in Liverpool and Louisa's brother, Henry Boult (aged 8 in 1881) was born in Barrow in Furness. His mother remarried in 1875.
It looks as though Louisa married a Henry Wood and was is Shropshire at the time of the 1901 census. The only Macaubrey in the 1901 census is James.