Hi Amy A,
I agree with EnglishCountryDancer, a diagnosis should be made by a neurologist or better yet a Movement Disorder Specialist (MDS). However, the symptoms you indicate do appear to be thoes of a PD diagnosis. Watch his tremor. If he only has tremor when the hand is at rest then this is more than likely a PD tremor. I also agree that at 79 it could be almost anything causing the tremor.

GregD