The father advised his errant son not to maunder about but do something worthwhile.

Answer: Option B

Trouble : difficulty or problems.
Wander : walk or move in a leisurely or aimless way.
Run : move at a speed faster than a walk, never having both or all the feet on the ground at the same time.
Play : engage in activity for enjoyment and recreation rather than a serious or practical purpose.
Maunder : move or act in a dreamy or idle manner.

Synonym of Maunder is Wander