“When I showed up that day, Brody was outside in a red wagon and his sister was pulling him around,” Mr. Simpson said. “I handed him a little gingerbread house with gumdrops on it, and it kind of spoke to him.”

Mr. Simpson went back to the house to add more decorations four days in a row. He also helped neighbors decorate their houses.

“My next-door neighbor, who only speaks Spanish, took down all her fall stuff and put up snowflakes and poinsettias, and did garland on her fence and lights,” Ms. Elliott said.

“When Brody saw it, he couldn’t believe it,” Mr. Simpson said. “He has been very animated.”