How to help my mum cope when her dad passes away ?

I have had experience with the loss of loved ones (my mums' mum). I was a little younger and even then it was hard to push a tear . I loved my nan however i can't cry or show much emotion when i feel the awkwardness of the death of a loved one. Its not that i am not feeling them its hard to show them when i see my parental figures crumble before me , People i remember being unbreakable . It ***** me up to see my mum cry and now i receive news that my mums' dad who lives over seas in China is starting to show signs that he is becoming more frail (he is very old )etc. I digress , What i originally wanted to ask was ; how do i take care of my mum when the time comes ...? How do i show her how much i genuinely do care when i can't show emotion? How do i not appear to be heartless when my mum needs my help the most ? . I fear my mum will believe she will have no one left after both her parents die i can't stand too see my mum that lonely and distraught. Thank you.