I thought that too re her occupation.
The only entry I see for Michael Harnett in 1924 is:
Michael Harnett, dairy, 18 Parnell Street.
It is the same in 1930 BUT there is this one in 1930
Harnett M.J draper 164 1/2 Capel Street
When I search for M J - there are the same later entries