In "Once Upon a Time," who would the parents expect to care more about the boy, his grandmother or the gardener? Whose actions hurt the boy and whose actions help him?

In Nadine Gordimer's story "Once upon a Time," the grandmother is surprisingly referred to as "that wise old witch." Nevertheless, the parents believe the grandmother has the entire family's best interests at heart, and they follow her advice when she tells them "not to take on anyone off the street" as a household employee. Later in the story, the grandmother helps the parents increase the height of the wall around their home by giving them bricks for Christmas. She also gives her grandson "a Space Man outfit and a book of fairy tales." The parents no doubt appreciated these gifts and took them as evidence that the grandmother cared for them and their son.
The gardener, on the other hand, is referred to as "itinerant," meaning he is not as steady a fixture in the family like the housemaid is. Still, he comes "highly recommended by the neighbors," so he is trustworthy. Because his duty is to care for the grounds, not the child, the parents would certainly believe the grandmother cares more about the boy than the gardener.
Ironically, however, it turns out that the gardener does more to help the boy than his grandmother does. The grandmother's advice and assistance to avoid association with the "other" ethnic group sets up a spiral of fear that leads the family to install the "Dragon's Teeth" atop the wall. She also gives the boy the fairy tale book containing the story of Sleeping Beauty, which inspires the boy to try to conquer the "terrible thicket of thorns." Thus, without meaning to, the grandmother harms her grandson. The gardener is the one who makes a valiant attempt to rescue the boy from the "razor-bladed coils," tearing his own hands in the process. Thus the gardener, who was probably himself of "another color," does more to help the boy than the grandmother does, even though his efforts to extract the child don't succeed. 
The roles the grandmother and the gardener play in the life and death of the boy present a tragic irony that reinforces Gordimer's theme of the danger of prejudice.