Question 12 in the Massachusetts Leagues' study of the Ballot Question Process asks "Should there be a period during which the legislature is not allowed to change a citizen-initiated law passed or repealed by ballot question?"
Currently, the Legislature may amend or repeal a law passed by the people (that is, a successful ballot initiative) at any time, subject only to the veto of the Governor and, of course, a referendum initiative. Most recently, the Legislature extensively amended aspects of the oversight, commercial establishments, and local control of the recreational marijuana ballot initiative that passed in 2016. In 2003, it repealed a Clean Elections Law that had been passed overwhelmingly five years earlier on budgetary grounds.
Some states place restrictions on their legislatures--delay periods, supermajority requirements, or even voter approval of legislatively-proposed changes.
Question 12 is on page 14 of the Study Guide.