I agree that it is quilting and my advice would be to continue in your grandmother's fashion with quilting 1/4" away from the seams around the squares.
The idea of quilting a 4 leaf clover may be appealing because it reminds you of her, but it is much harder to quilt than a straight line and I think you will find the quilting parallel to the seam will be doable and also attractive.
Doing the stitching by hand also increases the value of the quilt, whereas machine quilting it (in the eyes of an appraiser) would decrease it. She has some vintage fabrics in there, so it is something to consider.
If you wish to include the 4 leaf clover or honey bee, you can include that on a label on the back of the quilt, where you will also include her name and your name, and maybe some of the history and affection you had for your grandmother.
it will be a lovely gift and treasure for your mom!
Good luck!