They can't stop you attending by meetings as infinitum as a non baptised person.
Actually, they can. They can tell her that her implied invitation has been revoked and future visits to the kingdom hall will be treated as trespassing.
They typically do this when apostates come around and start asking difficult questions or start sharing TTATT.
Given JWs' strong bigotry against gays and transsexuals it's not too much of a stretch to think that they might do this to her if they sense she's intent on remaining a trans woman and is of the adamant view that Jehovah accepts her as such. They might consider her presence at the kingdom hall, dressed as a woman, as "upsetting to others" and a "spiritual danger" to the congregation. I think there's at least a 50% chance of this happening.
Keep this in mind: the very act of a biological man dressing as a woman is deemed by them as a serious sin worthy of disfellowshipping. So every time Allyson comes to the meetings dressed as a woman, the JWs - from their perspective - are witnessing a serious, gross sin taking place in their kingdom hall right before their eyes! From a strictly pseudo-logical, scriptural perspective it is comparable to a person coming to the meeting and publicly committing fornication at the kingdom hall in the presence of everyone.