The chemo will be hard on her, but it may shrink her tumors enough to make them operable. If there was no hope, then they shouldn't be doing chemo.
I think it's wonderful that you've invited her to be with you for the birth of your child. That is very exciting, and important to see the cycle of life.
Keep loving your grandma as you do. That will help her a lot.
Hugs to you and your family as well.