The protagonist has a dead mother, but she died before the start of the movie and her death isn't shown. It is, however, mentioned multiple times, and it's also implied (spoilers) that the protagonist let her die on purpose.
Starts at roughly the 12 minute mark, it's all on screen, ends about the 17 minute mark. If you want to completely avoid it, look away and turn off the sound once they enter her kitchen for lemonade.