Describe the setting of "The mother."

I think that the setting is a modern and urban condition.
Perhaps, using Brooks' own literary background might help
here:

The city is an
important and recurring symbol in Brooks’s work. She has created a series of portraits of women
inhabiting Bronzeville, a setting for many of her poems, which may be taken symbolically as the
African American community.

If this is
taken to be valid, then Brooks is writing about the condition that women who are economically
challenged and living in the urban centers must address. This would match with much in the poem,
where the speaker articulates the complexity within her decision. This indicates that there were
social and external conditions that played a role in the decision that the mother made and the
consequences of such a decision. The lack of hope that is present in these urban settings in many
an instance is where Brooks is at her most powerful in that she constructs a narrator that is
both a product and a representative agent of her condition. It is this setting where the
narration brought out helps to evoke a particular sadness in what it means to be immersed in a
condition where one has freedom, but little in way of control.