We have a couple mn options (no idea on a first name, though...) and one of them is a combination of my grandmother, Mary, and MIL's middle name: Elaine.
I've thought about Marlaine/Marlane (eh, it's ok) and Marilane (I like, but it may not go with many of our first name options).
Are there any other options? It's tough combining names to honor 2 people, but I think if I can, DH may go for a first name better