If you and yours are under attack and cannot safely escape, YOU are the only one who can mount an effective defense and counterattack (ATTACK THE ATTACKERS in order to STOP THE ATTACK).
Your awareness, mindset, training, equipment (that is ON YOU AT THE MOMENT, not sitting in the car or at home) and luck will determine what you can do and how effective you can be at stopping whatever and whoever is threatening you and your loved ones. Your concern is saving your own life and the lives of loved ones (and, incidentally, possibly the lives of others).
Awareness can save lives. Good decisions can save lives. Combative training can save lives. Weapons can save lives. Medical training can save lives. Medical equipment can save lives.
Do you have all those boxes checked? A lot of self-defense enthusiasts are lacking in those last two items. Imagine successfully stopping a threat only to watch yourself of a loved one rapidly bleed to death from injuries sustained during the attack, while EMS personnel are forced to stay back while police secure the scene (assuming anyone arrives before it's too late). Heck, there may not even be an attacker around to stop, as severe injuries could result from car accidents, household accidents, etc. Will you be trained and equipped to save those lives most important to you?
I highly recommend that if you're interested in protection of yourself and your loved ones, be sure you are trained and equipped to be a more complete first responder, not just an attacker stopper.
Here's a suggestion for a starting point: