Visiting last week in the funeral home, I heard family members say: "she's in a better place."
They have watched a loved one deal with chronic illness. They've sat near the bedside while "the work" of dying progressed-- nausea, wheezing, pain-- until the respite of morphine quieted the struggle.
It is never appropriate for you to offer a platitude such as "she's in a better place." But if the grieving express this to you, a lovely reply might be: " I'm glad that is a comfort to you."