I just don't know why Eren chose to save Bertholdt when his mom was going to die no matter what when the rubble landed on their house, but chose not to save anyone else.

I mean, if you're gonna mess with the past why why not save Thomas, Mina, Marco, etc. And then again, why stop there and not go full Madokami and prevent pure titans from ever eating people in history at all, erasing himself as a mere idea, only remembered by Mikasa and Levi?