Biographical information on the Internet is sketchy, but her Wikipedia entry contains the basics.
Here style is the slightly simplified naturalism favored by some artists in the 1920s and 1930s who either felt they had to adopt a little modernism for commercial reasons or maybe simply liked that particular look. Below are some of her portraits.
Harris was a leader of the famous (in Canada but, alas, not elsewhere) Group of Seven.
Holgate became of Group of Seven member not long before it disbanded.
I have no documentation, but assume for now that this portrait is of Holgate's wife.