What you name your child is up to you and no one else. If you like the name, go for it, and don't worry if she will be offended, especially since you don't have a close relationship that will be affected.
Most people would be honored to have a baby named after them, but that is a specific honor given because a person has had an important role in your life, and consulting the person would be appropriate if they're still alive and close to you.
Just using the same name is a much different story.
I would name my baby without worrying. If you're concerned, you could message her on facebook asking her if she would mind your using her beautiful name for your own baby.
If she's too distant an acquaintance for that, then when you make the announcement, you might message her privately on facebook telling her how much you've always loved the name. Most people would be happy for you.