Can’t blame her for collecting guns but perhaps when you have a crazy kid...you shouldn’t put a gun in their hands....just a thought.
We had friends who had a bipolar son of college age. They made the mistake of allowing him access to their hunting guns and he eventually killed himself. Some people just aren’t convinced that their “crazy” kids on meds aren’t a threat to themselves and others.
What we have here is a mental public health issue, not a guns are evil issue. I don’t know what law you can write to change it, since it gets down to personal responsibility.