Key questions in this regard are always "what is your investment goal" and "for how long do you wish to invest"?
Presumably, your mother aims to have the R250 000 grow appreciably, although with a lower risk of loss, over the medium term so that she might ultimately have a sum of money from which she can draw down to supplement her income in due course.
Let's assume that her investment horizon is at least five years, and her intentions are as I've described above.
A good default starting point would be a flexible unit trust fund. Unit trusts are a flexible, low cost and transparent way of investing.
In a flexible fund, the fund manager makes asset allocation decisions for you (i.e. decides how to spread the portfolio between shares, bonds, property, cash and international investments) so as to provide you with the targeted return (say inflation plus 5%) with a minimal risk of loss.
The return is not guaranteed, but if you invest for a period of three to five years or more, the likelihood of you achieving the required returns is greater.
You should select a flexible fund managed by a fund manager with a long track record of consistently good performance – that way you can derive some assurance that the process is robust and established.