as a LEO, i have some usefull advice, buy your dad a good can of O.C. for carrying in his pocket . Buy the largest one he can carry discreet. Second Buy your dad a large can of O.C. for in the house use, like the small fire extinguisher types. Give him a Sure Fire 6P or similar high power flashlight. Buy him a last ditch knife he can use to slash his way out of a life and death situation (SPOT, civilian, etc), get him a sturdy cane from cold steel with a steel handle. But foremost learn him to walk around in condition Yellow or Orange at night. Don't let the guys tell u that O.C. doesn't work , it does in 90 % of the cases. Criminals who stalk on older people are cowards. They will probably flee when met with resistance. I have have been hit with O.C about 10 times in my carreer during fights, it HURTS like hell !! I have sprayed a lot of people with it. If u have never been hit with a good squirt of O.C. u will **** yours pants , unless u are so stoned or crazy that even shooting won't stop u. The muggers are there for easy prey, they don't wan't to get hurt, they stalk, as al predators, the weakest or oldest of the herd. Make your dad look like a formidable adversary and they will seek another victim. Learn him to fight back with everything he has, he should never stop untill they are down and harmless or they flee the scene. Don't stop after a light squirt of O.C. and see if it has effect, spray him till he screams and his face is soaked with the spray. If he pulls a knife he will have to use it, NEVER display a weapon without the intent too use it. Good luck and send your regards too your dad.