Elderly people (including myself) do hide cash in the most unlikely places. Often it has nothing to do with not trusting banks, etc. but the feeling of safety in having some cash close by.
When my Dad died (over twenty years ago), , I found a brown envelope with a hundred pounds in notes hidden in his dirty washing basket. Just pure luck that I went through that, pulling out each item separately, to decide what to wash for charity shops and what to throw away.
Yes, I keep cash hidden at home (my emergency fund), but have also made sure that my daughter who lives nearby , knows where it is.