C.K.
Wow! It sounds like you really don't like her. Maybe your husband wants to stay out of it because he feels you're not being fair to his mom, and as a mother you should be somewhat understanding of his desire to protect his mom if she IS being treated unfairly. Im not saying she doesn't need to compromise, but in the "tone" of your writing there is in fact a lot of animosity, which Im sure is hard for everyone involved not to feel.
I've got an extremely overbearing MIL, who drives me nuts on a regular basis, and there was a time when my feelings toward her were very similar to what yours sound like. Because of it, my hubby and I almost split. We went to counseling and while I agree that in many cases he should deal with his mother, But in others he needs to stand up to me, and deal with me if I;m the one causing the friction, and I need to go to her to work it out.
It sounds like you have an aging MIL, who loves her grandaughter very much, and has some jealousy about the fact that your mom has so much time with her....(all not your fault, just stating the obvious). Weekends should be your time, that should be discussed nicely and with great reverence., but maybe you can sit with her to discuss this and find out some compromise so that she continues to have a second day during the week. You stated that she is 10 yrs older than your mom, and has health issues, she's probably having a hard time with facing her impending demise(perfectly natural) and is probably jealous that your mom will have an extra 10+ years with the grandaughter, maybe even get to see her graduate and get married. That can be really hard and Im sure you can see why she would be jealous, and somewhat needy. This is your husbands mother, and the grandmother of your child. This is the one and only chance they have ot bond, LET THEM. These relationships are worth making an effort for, as it will provide your daughter with happy memories, and will help an older woman experiance one of the greatest joys in life-Grandchildren. You'll see once you become one, but all grandparents get jealous of one another, especially if, for whatever reason, one gets more time than the other. This is totally normal and your MIL is not some Special Evil sent just for you. Be nice to her....Nice really does go a long way, and you'll be teaching your daughter a valuable lesson, through your actions.