When you compare the first and the last picture of the game, you see the same face of Aerith. My guess is that there's a cycle here, and it restarts right in this alley. The same cycle that ended up with the destruction of the Cetra* long ago (*the children who left the garden of Eden to enjoy sedentarity and technology). Same mistakes, same result.
To me, Mother = Mother Earth = Aerith
Did you see how she is chasing Cloud in the new trailer ? She needs him to fulfill her plans.
Really looking forward to play this new game