Paradise and Nanako

So, i just beat Paradise and Namatame and, wow, that dungeon is so perfect. The music and the whole design was so great.

When i saw Nanako calling her mother i felt so sad, some months ago i lost my mother and my whole life changed. I also feel alone sometimes even that my family is still here but it isnt the same without her...

Anyways, i saw that we need to something with Namatame in order to Nanako survive in December. What do i need to do?