Gender therapists are excellent with this sort of thing to help you and family members alike, but if there's no therapist here are a few good articles that I showed my mom if you haven't seen em yet...
http://community.pflag.org/document.doc?id=495 (lots of other great pflag publications for families
here)
http://web.uvic.ca/~ahdevor/14StagesBLOCK.pdf (helps if you highlight the parts that you connect with)
You could always try to get her to use this website, but honestly (at least for my mom) I didn't think it would help as much as just talking to her and educating her myself given my own specific situation. I did tell her about susans, too, and she was happy hearing about it but didn't seem that interested in using it herself.
However, I'm sure if your mum posted a thread here and had questions, the members of this forum would be MORE than willing to help answer her / provide peace of mind / support both of you in the kindest way possible.
Do what seems right at the time. Maybe just try showing her the forums as a way to reveal the vast layers of international support that we all have being trans*? If she seems interested in getting involved then sure it's a great idea!