The 1878 one was born on 31 January 1878, so she would have had her 23rd birthday by the date of the 1901 census.
The first one in 1879 was born on 12 January 1879, so would have had her 22nd birthday by the date of the 1901 census.
The other was born on 6 June 1879 so would not have had her 22nd birthday by the date of the 1901 census.
So assuming that she was Elizabeth Fisher, and that there were no more unregistered Eliza(beth) Fishers born in Newownards in 1878 or 1879, and that she had reported her age accurately, she has to be the second one, whose parents were James Fisher and Mary Eliza McKee.
