First, Welcome to FTF.
I'm dealing with an elderly parent also,(96, God bless her) and it can be very trying as they slowly and agonizingly become less than they once were.
I can't tell you what to do, but I can tell you what I do.
Any gun which is not currently "under my thumb" as a CCW is unloaded, period.
Any gun upon which I'm not working or taking out to the range soon is locked
away in the safe(all ammo, in the safe). Any gun not immediately going to the range, or hunting,(in most situations it stays cased until it's in the car) is disabled and locked open.
So, in order to make a gun fire-able at my house, one has to
1.-get it out of the safe(as well as the proper ammo)
2.-remove the locking mechanism
3.-load and chamber a round...
...not an easy task, since I carry all the gun keys.