It seems to have happened on May 12, 2018. This seems like the raw video from the first uploader and that is the date they gave it.
The Story(pieced together - nothing solid),
Location: Sao Paulo, Brazil Outside of a School
The Robber: Dead
The Mom Shooter: Police Officer, Off-Duty
Firearm Make and Model: Uncertain (Probable Glock)
Meme: The Only Thing That Stops a Bad Guy With a Gun is a Good Guy With a Gun
Source: YouTube
Query: Woman Shoots Robber
▶️ DTube
▶️ IPFS