A cane could be an option, depending. But then there's the legal aspect, but if you are older and unable to defend yourself physically, and can defend that it court, disparity of force may be on your side. I don't know for sure on that, so don't quote me.
As for empty hand techniques, it really comes down to why you need them. I'm young, have had a lot of experience in Martial Arts and real, albeit stupid, fights. So, I can't touch on self defense in later years, but I'm thinking a lot of basic escapes would be first. It doesn't take as much strength, or even speed sometimes, to accomplish. Add a face shove and it can buy a bit of time.
As for the content of the original post, falling is more common and just as dangerous as a violent situation. There was a study done not too long ago about the elderly falling and getting hurt while the young usually don't. They came to the conclusion that since people USUALLY don't practice falling, they don't know how to react accordingly. They started a course to teach people to fall safely in hopes of preventing injury. I've not heard anything about it since, but I thought I'd mention it.
"Today is victory over yourself of yesterday; tomorrow is your victory over lesser men." - Miyamoto Musashi
[Insert random irrelevant religious quote here]