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The son is the subject (nominative), the question is the direct object (accusative), the mother is the indirect object (dative). "The son" is putting "a question" to "his mother."
To me "ask to" doesn't sound right. I don't think it's wrong per se, but it seems unidiomatic; it would normally be "asked his mother a question" or "asked a question of his mother". It may be dialectal or something though.
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