I would use flannels, patterns easy on the eye with the colors your SIL loves. A simple pattern in order to get your present for her done ASAP. She can wrap herself in a soft, warm cloak of love made visible. It will mean so much to her .........
No to the M quilt definately. Know you want to show love but the host of mixed feelings may never be resolved for her. She will never need a reminder as she will always think as we all do that there was something she (they) could have done to prevent her death.
I think you exemplify the best in quilters on so many levels.....
Cindy