First we must understand that Dewey Dell is pregnant with Lafe's child, at 17, out of wedlock, in a strict Christian southern home and time era.
Mosley is a pharmacists that Lafe advised Dewey Dell to see; Lafe suggested that Mosley, as a pharmacist, would have drugs that would assist Dewey Dell in aborting her pregnancy. Mosley's stern advice comes from a strict Christian and southern background; he tells her to take the $10 that Lafe gave her to obtain abortion drugs and buy a marriage license.
Mosley offers such advice because of his background, but mostly because of his reputation. After Dewey Dell states that Lafe suggested she visit a pharmacist, Mosley becomes very flustered trying to assure that he was not being associated to abortions directly by name. His concern is mostly to maintain the appearance that he wants to help people.