This stuff really should be taught in school - although exact conditions will change over time, the general principle that you need to check your rights & responsibilities should be made clear.
In conversation with WASPI women, I have wondered how I knew about the change in pention age, contribution rules and changes in NI payments over the years I was employed. I realised that my parents taught me to keep myself informed and check my situation.
It is very sad, as appleseed could have been paying voluntary & self-employed NI over many years. It is correct that they will not be completely destitute, but will be reliant on benefits.
I have come across a few people like this before - they are often people who hold themselves apart from a system they either don't understand or think doesn't apply to them (I don't know where appleseed is in this). Over the years that appleseed acted as an unpaid carer, they have presumably saved the State a great deal of money, but it sounds as if it was completely off the grid, with no formal recognition at all. I think it would be almost impossible to claim in retrospect. Please appleseed, contact one of the organisations that can help you.