In your friend's position I would suggest to the "children" that they could buy the house collectively from her, so that they keep the house they love so much, and she gets the funds that she really needs to provide for her own future.
I am basing that on them feeling sentimental about a family home, rather than just seeing pound signs.
If they collectively bought it, they could rent it out to cover the mortgage costs so not being adversely affected themselves, but still having the family home within the family.
If they refuse, they can always draw up a rota to provide care for her when she needs it, and to carry out repairs/maintenance and gardening for her. (I suspect that won't happen.)