I am so sorry to read this. So heartbreaking.
At 17 it's going to be incredibly difficult to pry your daughter out of your malevolent mother's hands, since she's managed to get her on her side.
Do you know how she's managed it? Has she indulged her and made out that you're a nasty person who doesn't care about her own daughter? Turning you into a black demon from hell? Has she just bribed her?
I know that occasionally people have managed to get their children back, usually after some time when the children themselves see that 'darling grandma' isn't so darling after all. But it's not easy and it doesn't, Im afraid, always work.
I think that you can only send your daughter the message that things aren't always what they seem, that you love her and that you hope she will be willing to talk. And then give it time.
Would your mother destory / steal any presents you send her? It might be an idea to say that her xmas presents are here, at your own house, for her to collect.
I mean this very gently, but sometimes people who have been brought up by a malicious person make mistakes in their own parenting. They mean nothing but the best, but with such a terrible example they don't have a good role model. Again gently, it might a good idea to think about your own parenting from the point of view "could you give her steady love, time, loving and fair boundaries". If you have fallen significantly short in some areas, then it's worth acknowedging that to yourself and perhaps, when the time is right, to her but saying that you always loved her and wanted the best for her.
Therapy is probably a really good idea. The level of pain your mother has inflicted on you as a child and now as an adult has to be huge. A skilled therapist can help you understand some of that damage and heal from it.
I hope that things improve for you and your daughter @DenimDrifting Some people like your mother should be kept far away from children.