You are in a special need situation. Your situation does not fit the bug out or wilderness survival situation. You have to stay in contact with civilization to keep a continuous supply of medicine for yourself and you grandmother.

It sounds like you are describing a shelter-in-place scenario. You have to take care of you grandmother. You are also dependent on medication yourself. Your goal seems to be to be able to get back to you grandmother if some emergency happens. Then you need to be able to shelter in place for an unspecified period of time. I can not see you being able to bug out. It is possible that you and your grandmother could be required to evacuate to a shelter.

I suggest you check out Ready.gov http://www.ready.gov/index.html they have all the information you need to make a good plan and what supplies you need.

I don’t believe you would be in great need of a survival firearm. Everyone that is able should have a self-defense firearm. There is a reason most police carry Glock pistols. They are very reliable. Tell us about your shooting experience. How powerful of a handgun do you feel confident shooting? Do you have the mindset to defend yourself or your grandmother? My wife for example keeps telling me that she would not be able to pull the trigger even if it was to save the life of her children. I suspect “mom the protector” hormones would kick in. If you can not see yourself pulling the trigger then you do not need a self-defense weapon. You might prefer a less-than–lethal weapon. Pepper spray and SureFire lights come to mind. Your tactic would be “stun and run.” Stun the bad guy with the pepper spray and run to someplace safe and call the police. Many of us here have a CCW and live in a strong man state. Plus us older guys would rather shoot than run.

Let us know what you plan to do for different emergencies and I am sure the people here can give you excellent advice on what to have and do.