I've answered Tremors with outstreched hands thinking that it might be something sinister regarding cerebellum. Needless to say I was wrong.
I believe the answer should be memory loss for the following reasons:
1. Age= She is 70+
2. Lifestyle impairment = She got lost while shopping and forgot to turn off the stove
With the above mentioned points we should suspect Alzheimer's or other causes of dementia in general.
Loss of DTRs at ankles is normal part of aging as per Uworld Step 2 CK. Same can be said about decreased vibratory sensation.
High frequency hearing loss is part of normal aging called presbycusis if i'm not mistaken.
And last but certainly not the least, tremors could be explained as essential tremors. The description of tremors does match cerebeLLUM disorders but the fact that I got it wrong would mean that it could be less sinister.
Hope this helped.