The minister sends for Miss Emily's relations (female cousins) because of her seeminly inappropriate behavior with Homer Baron, a carpet bagger-type from the North. They are seen riding in carriages without a chaperone which is not considered proper behavior for an unmarried Southern lady like Miss Emily.
Homer Baron is a northerner who is spending time with Miss Emily. They are seen together in public and the rumors fly that maybe they will get married. Miss Emily has bought a set of gentleman's toiletry items engraved with Homer's initials, and he disappears shortly after Miss Emily is seen buying poison for pole cats and rats in the local apothecary's shop. Not long after that, the local men are having to spread lime in Miss Emily's yard because of the horrible smell of death that has gathered around the home. Unable to investigate because it's not right to tell a Lady that she smells, the men did this under cover of darkness.
Later, after Miss Emily's death and Toby's disappearance, the corpse is discovered with a long, iron-gray hair on the pillow beside it indicating that Emily and Homer had actually "married" in some sense of the word.
One of Faulkner's most obvious themes in "A Rose for Emily" is the struggle between tradition and modern thinking. Emily represents the aristocratic Old South with all of its idiosyncrasies. When she, a Southerner, begins dating a middle class Yankee, the minister's wife and other townspeople see this as a serious threat to their traditions. She sends for Emily's relatives so that they can bring Emily back to her traditions and her deceased father's views.
Homer Barron is Miss Emily's male friend or love interest. Faulkner is unclear about how serious Homer is about Miss Emily, but she definitely plans to hold onto him. Homer disappears the first time shortly after Miss Emily's relatives arrive in town. Three days after Miss Emily's relatives leave her alone, thinking that they have accomplished their goal of running off Homer, he reappears. The last anyone sees of Homer is when Miss Emily's servant "admit[s] him at the kitchen door at dusk one evening."
The minister's wife, along with the townspeople (who are narrating the story), is offended and shocked at Emily's forward and uncouth behavior in regards to Homer Barron. She is breaking conventional dating rules, and being improper by spending too much time with him. The story states that the people thought that Homer was below her station because he was "a Northerner, a laborer," and so it was inappropriate to be seen with someone so poor and unapproved. They spend so much time together that they believe "that she was fallen," which is a nice way of saying that they think she had slept with Homer. Her continuing to spend time with him in public "was a disgrace to the town and a bad example to the young people," so the minister goes to talk to her, and leaves upset, then the minister's wife writes for her aunts to come to town. They want Emily to have a chaperone in the house so that nothing improper can happen. They want Emily to have guardians, and someone to enforce "proper" behavior, and family around to try to convince Emily that she needed to marry Homer to make their relationship legitimate. So, the minister writing was a way of meddling in Emily's life, because the townspeople thought she was behaving inappropriately and being a bad example. I hope that helps.