Emily Mary was born 5 years after the death of Robert Evans, who was obviously not her father. The 1881 census shows Ann as 'married' not 'widow' so it is possible - though not likely - that she remarried another Evans who was not present at 1881 census time. Another possibility is that Emily was the illegitimate daughter of Ann's youngest sister Maggie, who was living with the family in 1881 - in which case the father may even have been Ann's son Evan! Many possibilities.