Madoka's wish seems to be the most likely to do that really, because she said she had essentially unlimited potential, and stipulated rewriting the rules if it was necessary to serve the purpose. What is more important is that Madoka wished to personally prevent the creation of every Witch ever,
and that magical girls had invariably turned into witches up until Madoka's time. Thus, Madoka has the ability to go into the past part of ever without depending upon Homura's control over time.