You are an awesome son to do this for your Mom. I know she will love it no matter how you decide to finish it. One of my thoughts was to split the blocks in the second picture & add half to the top & half to the bottom of the first picture with the dark border around all of it. Then add to that with blocks make by you & then a few more boarders. For quilting it, I would do a cross hatch pattern. You will want to pick up a walking foot when you quilt it though. Will make it so much easier for you to quilt plus adjust your stitch length longer. No matter what you decide to do, it will be treasured by your Mom. Just remember, there are many ways to do quilting, so please do not let someone try to tell you there is only one right way. Whatever works for you is the right way.