Tell the person who lost their grandmother how sorry you are for their loss.
Tell her loved ones condolence and sorry for their loss.
You have come to reliase that your grandmother was older and she wont be around forever, and you have to accept that so that you can handle all the people. And tell them sorry for their loss.
Give a the person a shoulder to lean on, and comfort her. Give time for grieving and respect the person's feeling.
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