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Yea I doubt that would be the case. Barangay Love Stories has one who tried to prepare for their own death, much to the chagrin of their friend, only for the latter to turn out to be the one to die.
In my view, the only thing to be said is that it's a sort of cosmic/fatalistic cruelty, since not even any character orchestrated these events. So that trends toward Cosmic Plaything (if this sort of thing has often happened to the grandmother; just a one-time event doesn't really qualify) or Twist Ending or Cruel Twist Ending (depending on how bad the child's death is).
Edited by KD

I.e. the main plot point of the 2003 drama film Magnifico whose child protagonist prepares for his grandmother's (presumably) impending death by making a coffin for her, only for the child himself to pass away and be buried in his own coffin.