This isnot a mental illness. This is just complete ignorance of gun danger in a country that celebrates giving out firearms like candy without any kind of training or licensing requirements. This is a dangerous lack of gun laws and an ignorant gun owner. Here in Canada, we have lots of guns but a far lower rate of accidents and murders. Pistols are restricted, which means the only places you’re allowed to ever have a pistol is locked in your home, at the gun range, or at the gunsmith, or locked in truck on a direct route between those locations. You aren’t allowed to keep ammo in the same container as the gun, never mind keeping one actually loaded. You know all of this because you had to take a safety course and pass a written and practical exam before you are allowed to own even a .22. The restricted license is yet another course and set of exams.
This is the fault of the laws of the land and the mother’s ignorance. Don’t bring mental illness into it, that’s ablist bullshit.