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.