"No cure" ?
The way you talk about it is a bit like you bow down to it. As long as you work with Energy, there is always something happening mtthwoh.
Now,your business in Healing is to make sure you keep on working at sending harmonious vibes and thoughts towards the patient(s).
You might want to remember that you are not the one doing the work

As long as you keep on steadily with your energy work, things will be fine. because you have no idea if the Light you are sending will be used to help the patient(s) carry on elsewhere, so to speak, or they will use your Light to stay here.
Regardless of how powerful you are as a healer, that you have no idea to know.
So please don't feel like you have lost a battle because somebody you pray for doesn't recover straight away. You don't know their Karma and what's happening "behind the scenes" .
What you can do is send Light & Love to them and wish for that Energy you send to be used the best way .
Being a healer is also that...to be Hopeful, not "realistic" because what people call reality doesn't include Energy and its subtle effects.
I repeat
Healers don't deal with "reality" as most people think.
Yes, you can help spare your mum pain, it is by making sure you are steady in your Energy work, regardless of the appearances.