In general, when they recommend Hospice, your condition is similar to those in which people might be expected to live about six months or less. That doesn't necessarily mean that's accurate. What Hospice means is that she's giving up active treatment towards a cure in favor of other goals-- comfort and quality of life at what is expected to be the end of life. There are various things they can try for pain management. My dad is not yet on Hospice care, but he is using morphine in pill form, extended release. He has experience with IV morphine when he had his previous lung cancer surgery. That was potent stuff that really zoned him out. But we don't have any experience with liquid oral morphine. I think they use it in Hospice and palliative care because it's easy to give. The people who are in the best position to answer that question for your grandma's case are the Hospice care people. I understand that they are usually very good at communicating with the family as far as what to expect, and what to look for if it's near the end. Best wishes to you and your family.

We took care of both Mom and Dad, 10 months apart in Hospice care. Both had cancer, giving morphine doesn't really mean it's near the end, it's just a strong pain killer, and easy to give and to take. With Mom, she was given a small amoount every 4 hours for a few months, as she started to get worse, and pain was getting worse the dose was raised. In her last week, we were giving her hourly doses of a heavier dose. She was very peaceful, and not in pain.
It's a hard thing to do, but I am glad that we were able to be there with her, taking care of her and being sure she was not alone.
We wish you the best in a difficult situation.