What, specifically, is Brent’s punishment for his crime as set forth by the parents of the victim?

Mrs. Zamora, Lea's mother, doesn't believe in retribution—not even against Brent, the young man responsible for killing her daughter. Lea's mom grew up in the Philippines during the civil war and saw firsthand the immense damage that revenge can do. However, she does think that Brent should still be punished in some way, just not by conventional methods. Instead, Mrs. Zamora devises a novel punishment that will hopefully make Brent face up to his responsibilities while also doing justice to Lea's memory.
Mrs. Zamora can never bring Lea back; but she can still keep her spirit alive, and the way she wants to do this is by getting Brent to make four whirligigs of a girl who looks like Lea and placing them in Washington state, Florida, Maine, and California: the four corners of the United States. That way, people will still be able to receive joy from Lea—that's what she would've wanted.