、？
Hey kiddo, where's your mom?
Literal
Little-boy, honorable-mother [topic-は] where-[assertion-だ] [question-い]?
A window into older or regional masculine speech. 坊や is an affectionate address for a young boy. 何処 (どこ) written in kanji gives an old-fashioned feel. ~だい is a masculine question particle built from だ + い, common in older fiction and informal masculine speech; modern equivalents are plain ~？ or 何処なの？. The whole sentence sounds like an elderly man addressing a child in a drama or novel.