It's impossible to say. Based on the rash, probably at least stage 2. Normally when symptoms are showing, its passed stage 1.
The good thing about Lymphoma is that it is highly curable at all stages. Even if your friend ends up at stage 4, she has a very good chance to make a full recovery.
They wont know the stage until she has a full body CT scan, as well as a bone marrow biopsy.