In 1891, she is at 43 Loch Promenade, Granville Hotel, Douglas (RG12/4688 134 pg 26 #133). On Ancestry she was indexed "Harf" (I submitted a correction in February) but it says: Elizabeth Scarf, Serv M 48 General Servant, b England. The head and wife are Gustave S & Mona NALTAN 53 & 52 Hotel Proprietor, b Germany.

Brian Lawson's burial index has a burial 7 Jun 1928 age 83 Elizabeth SCARFF Douglas Burial Cemetary. It would appear that she was born about 1843-45 but "England" is all we have so far. She would have been about 40 when she married, so could easily have been a widow. I briefly looked at Smiths in earlier IOM census's and it's quite possible one of them is her. Have you checked those out?