The entire Mario Bros. franchise is typically very family-friendly and appropriate for kids. Games in the series that are appropriate for very young children include the "Mario's Early Years" series and the "Mario is Missing!" games.
The "Mario's Early Years" games are a spinoff educational series that teach letters and numbers to children not yet in school. The "Mario is Missing!" games teach geography to slightly older children.
It is unlikely for parents to find content objectionable to them in any Mario Bros. game. The only question is whether the parent approves of video games and if the child is old enough to understand how to play and handle the controls.