Annie, not sure on Ethel Hall at all, other than that census entry ref for her from 1911 at George's household in Ireland.
The person who died in 1919 at Melville Road, Ladybank, informed by George Magee, was his sister Ethel Elizabeth Magee, single and aged 46. I think that is the only fact we have so far on this Magee family.
Monica
Added: Just realised too from that 1911 entry in Ireland that Ethel Hall, was widowed and born in England. A few 'creative' possibilites working off mother being possibly Ethel Hall. Restricted online from checking as births for 1915 not available to view until next year with the 100yr privacy rule. Frustrating as always...