you don't need more than one handgun to defend yourself
I'll explain this slowly.
The second amendment, in case you're not aware, mainly exists so that citizens can be armed and readily have the means to fight a tyrannical government (which you lefties keep saying the current government is), or a foreign threat, if the needs ever arise.
Which means that citizens need to have access to weapons which would effectively allow them to somewhat actually be able to fight back against the army. Guess what? You don't do that with handguns.
Now, does it sucks that a TINY, infinitely insignificant amount of nutcases decide to forego the law and decide to shoot people? Absolutely. But you'll find that no matter how many laws you put in place, you will always find a few bad apples that will break them for their own benefits, whether it is financial, moral, or ideological. I am with those who believe that punishing the overwhelming majority who respect the gun laws, due to the action of an insignificant amount of people is idiotic at best. And no amount of lefties outrage will change that.
Don't bother. She probably thinks it was made for hunting deer, or that "only muskets" existed back then, completely ignorant of fireams. Here is a list containing a few.
Also, contrary to popular belief, the Second Amendment is not just about firearms, but all arms in general (such as bladed weapons or heavy artillery).