Acceptance has to be the biggest healer for grief, I know for me when my mum's mum (grandma) passed away it was hard because she had formed a big part of my early life. And then when my Mum passed away, that was a very mixed emotion because she had been unwell for many many years and dealing with that and seeing her pain made it always a warped relief.
Life will always have many challenges, how we approach and overcome them it was defines us as a person.
What you just said about your Mum reminds me a lot of my emotions when my father passed away. After much pain, there was relief. It happened in a moment when there was hope again, that he could maybe recover.
That made me question my hope, where it came from. Made me question myself. Since that time, I reflect much more on my emotions, especially on hope and where it derives from.