The only sort of investment with zero risk to capital is a bank account. You can get around 3% gross on 12 months bonds with various building societies / baks - more if you are willing to tie the money up for longer. Bonds are not, of course, completely risk free, but are almost zero risk. Risk is not a digital thing that is either on or off.
If one has had a trust set up, as far as I know, one has no choice than to make trust returns - its one of the penalties of having the trust versus the upside of avoiding tax/financial penalties/whatever, of life without the trust being set up. In this case it sounds like the trust was set up to avoid the capital being eroded and thus forcing the State to pay for someone with care fees who would normally have the resources to fund it themselves.