The two men are on the property to make a film about the county's food stamp program.
In the story, the two men are referred to as Camera and Smilin. They ask Granny Cain for permission to take pictures of her property. For her part, Granny Cain isn't overly enthusiastic about the request. She feels that the men have trespassed her property and also crossed the boundaries of common courtesy.
Although Granny Cain quietly tells the men to stop filming, they ignore her. They insist that they are there on behalf of the county and even ask her to make a statement for the film. One of the men comments upon Granny Cain's garden. Although his words are cut off, we can make some speculations about what he was trying to say.
“Maybe there’s somethin you want to say for the film. I see you grow your own vegetables,” he smiled real nice. “If more folks did that, see, there’d be no need—”
Essentially, the men want to find out whether the county food stamp program has been effective. Perhaps, based on the quote above, they are trying to substantiate the necessity of the food stamp program. The author does not provide more details.
What is plain, however, is that Granny Cain does not appreciate the presence of trespassers on her property.