The lines in the story relating to the question are the following:
The wife could never see anyone go hungry. She sent the trusted housemaid out with bread and tea, but the trusted housemaid said these were loafers and tsotsis, who would come and tie her and shut her in a cupboard.
Gordimer uses irony in this instance, for it is ironic that the wife appears to be more trusting of the unemployed vagrants than her maid. One would expect the reverse, that she would be more suspicious of them and that the maid would encourage her to help them.
The extract illustrates the difficult societal situations and conflicts which were created by a legalised system of oppression. In the first place, whites, in terms of the apartheid system, were placed in a superior position and could partake in all the privileges such a system granted them. All the other races were classified as second- and third class members of society. This obviously led to enormous disparities in the socio-economic status of the different racially classified groups.
Since white people were a privileged class, it was logical that a great number of them would adopt an air of superiority and they would look down on the less privileged (which would be the other racial groups). Added to this, was an almost paternalistic and patronising approach by the whites to the less-privileged. Their actions were not necessarily guided by a sense of goodwill or an obligatory duty to help, borne from pity or care, but because they felt, being superior, they could be patronising and provide for those in need. There were obviously, exceptions.
Further irony lies in the fact that because of the huge disparity, the less privileged classes were forced into subservient positions and this led to exploitation and abuse, so much so, that survival became a desperate struggle. Many earned a pittance and lived in impoverished conditions. In the townships which were created for the underprivileged classes, gangsterism and other forms of criminal activity were allowed to flourish, creating fear and suspicion for ones own kind.
These are the truths exposed by the extract. The wife's act of kindness is borne of the patronising and paternalistic views espoused by members of her race, and the maid's cynicism is informed by her experiences in the township. Both are intent on self-preservation. It is ironic that the false disparities which were created by apartheid should have them behave in this manner.