2015 AMC 10A Problem 4

Let $m$ be the number of candy eggs that Mia had. Then Sofia had $2m$ eggs and Pablo had $6m$ eggs. The total number of eggs is then $$m + 2m + 6m = 9m.$$ For all of them to have the same number of eggs, they each must have $9m \div 3 = 3m$ eggs. Sofia needs $3m - 2m = m$ more eggs. This means Pablo must give $\dfrac{m}{6m} = \dfrac{1}{6}$ of his eggs to Sofia. Thus, B is the correct answer.