Great uncle

[Forfarian]

Is this just a coincidence or could GFE have been a twin 
GFE Year 1921   Ref 178/ 6     RD Name Cairnie
GFE Year 1921   Ref 152/ 21 RD Name Enzie
MME Year 1921   Ref 178/ 7   RD name Cairnie
MME Year 1921   Ref 152/ 22 RD name   Enzie

The reference numbers are consecutive in both cases so yes, they are twins.

Mina McKay Ewen or McLaughlin died in Elgin in 1966 aged 45. Her death certificate, unlike that of her twin brother, should tell you the names of her parents. Unless the quoted tree is correct and she was illegitimate and her father's name is unknown, in which case it will only give her mother's name.