umm...could you leave it as it is.... but on the right side add a simple border with some hand embroidery on it? Maybe something like "given to me by my grandma." You could hand embroidery a few hearts on it too?

If you want to see how the points would look spread out, this youtube shows it.

https://www.youtube.com/watch?v=0rsGEwrkITE

First of all I would not change anything that is there. No matter what you do, both sides will be different. A wall hanging would be the most logical to use the hanging strips. I would choose a color to match. It could be the orange or the brown (I prefer brown) and make a ruffle and attach it on the cut side. I think the asymmetric look would be charming.

As Toverly said, I too wouldn't cut anything. I would ask her what she would like to happen with her grandmother's heirloom. I think I would hand stitch it to a background fabric and quilt little hearts to attach it to the backing. Bada bing a wall hanging:)

Certainly her tiny quilt is a treasure! I love that you are happily helping her!

If I had the challenge in hand, I would first do some careful measuring to see if the ties are long enough to create additional prairie points. If not I would carefully remove the prairie points and remake them in unbleached muslin. It would fit with the color scheme. I agree that it appears to be part of a whole not an individual piece itself. And as others have suggested turn the piece into a pillow/pillow cover that can be displayed with loving pride.

Can you remove the ties, give them a good pressing and use them to cut prairie points to put on the blank side. Then remake ties from another fabric that blends with the Sunbonnet Sue?

Please don't cut off the prairie points if you want to keep the memory for your friend. Maybe cut off the ties. A quilt doesn't have to be perfectly square to be useful. Find a fabric that coordinates with the brown and use it for a backing and stitch a strip of that fabric over the raw edges of the yellow top.
Here are a couple of ideas:
If you want to make a pillow cover, stitch the unsewn edge into the right hand seam of the pillow cover and hand/machine stitch the other edges of the yellow piece onto the top of the pillow cover.
Stitch the yellow piece to the background of brown and add a strip of the background fabric to cover the unsewn edge, leaving enough background all around to make a pillow cover, turn it into a wall hanging or stretch over a frame. In all cases, let the girl and the prairie points shine.

a similar or darker yellow shade would look fine. you may have to start above the left bottom corner, looks like it needs redoing there and then add darker to bottom and right side. It is nice of you to do this for her and i'm sure she will appreciate your efforts.

You could suggest to your friend that she could frame it to preserve it as is. She could loom at it every day.