I see in the 1910 census that they are residing at 395 Warren St. and Nellie REDDY is a laundress.
In the Brooklyn Daily Eagle of 1908 there was a "Mrs READY" of that address advertising for a washing and ironing position (see attached).
And.. in the NY City marriage index:
Clyde S. Stuart and Gladys Irene Ready, m. Aug 11 1918, certificate # 9074, Kings County Brooklyn.
We can see how old that Gladys READY was in the attached marriage notice and that she would match the age of the Gladys REDDY in the 1910 census who was residing with her mother Nellie.
The marriage certificate of Gladys (Ready) Stuart will likely show the names of her parents.