I'm very sorry for your loss, my father died seven months ago at the age of 88 leaving my mother, who is in the early stages of dementia, so I understand what you're going through.
"We're not talking huge amounts on money, maybe a few hundred thousand plus the family home."
Having said that, I really am sorry but "a few hundred thousand" on top of a family home is in no way not a huge amount of money.
In this situation, assuming that your mum's will says that everything goes to the children, then anything over £1 million will be subject to inheritance tax at 40%.
I don't know what exactly you mean by "a few hundred thousand" but let's assume that it's about £300k. That's on top of the value of the house. Do you have any idea of the current value of your parent's home?
Let's say that the home is currently valued at £1 million. So, in this example, if your mum were to pass away tomorrow then HMRC would expect the executors of the estate to pay £120,000 in inheritance tax.
However, this can be reduced if she makes gifts to her children and she survives for more than seven years. In this case these gifts are not counted as part of her estate and so will reduce any inheritance tax payable.
So, you have a bit of a balancing act to perform (if you are at all concerned about paying inheritance tax - if you don't care about it then don't worry).
As others have said, you really do need to speak to a qualified advisor about this. They should recommend a mix of investments, some of which concentrate on capital growth and some which concentrate on providing income.
This will provide an income for your mum and also the capital growth will then mean that, in the future, more can be placed with the investments that concentrate on providing income so that your mum's income is inflation proofed.
It's similar to a pension. You can either get a larger amount that is a set amount every year or a lower amount that is index linked and will increase over the years with inflation.
If your mum's situation allows for it then it may also be worthwhile at some later stage of her making gifts to the children to reduce any future inheritance tax liability. Don't forget that it's 40% on everything above £1 million.