There is no definitive answer to what Dill's parents have done about his running away in Chapter 14; however, the reader can surmise that very little probably has happened. Dill's parents are simply not interested in him; his mother has remarried and is preoccupied with her new husband, who disparages Dill by saying to him,
You're not a boy. Boys get out and play baseball with other boys, they don't hang around the house worryin' their folks."
Dill tells Scout and Jem that his mother buys him books and whatever he wants, but she expects him to go play with it and leave her alone. In the summer she sends him to his Aunt Rachel's; fortunately for Dill, he has made friends with Scout and Jem, so it is no wonder that he runs away to Maycomb.
When Scout asks Dill why Boo Radley does not run away, Dill sighs and responds, "Maybe he doesn't have anywhere to run off to...." indicating his own unhappiness.