I felt led to make a suggestion for you and your friend. It's a technique I used when I was doing birthwork in Texas.
When I had a young mom whose own mother had died early in the pregnancy, she was so sad that her mother would not be at the birth to see her first grandchild. I encouraged her to close her eyes, take a deep slow breath, release it slowly and relax. Then I asked her to imagine she was in the hospital birthing room in labor. She was to "see" her mom sitting beside her bed, imagine the color/design of the clothes she was wearing, what shoes were on her feet. Had the mom had her hair done in this picture? Was she holding the young mom's hand? Did she look happy? I asked the young mom to imagine her mother helping her feel more comfortable, speaking words of love and encouragement to her.
Weeks later, after the birth, the young mom told me how she had "felt" her mother with her throughout the event and how much it had meant to know she was there because she had "seen" it in our work.
Perhaps your friend might benefit from a similar exercise in visualizing her mom finishing this quilt, or watching and approving as you finished it *with* your friend.
Hugs to you for doing the quilt for your friend.
Jan in VA