It is sad and a scandal how those elders and this organisation treats your mum and you. But that's their procedure.
I told them openly that i would accept blood for myself and my son and also the reason why i don't agree with their view of blood. They couldn't df / da me because I did not take blood, just hypothetically told them i would.
Your experience shows that they have no heart and care only for their bloody rules.
But why not look at it from a different view:
You and your mum could take this whole sad experience as a trigger to really leave. In all of this maybe your mum realizes that there is no real love in the org and that their rules are killing people. Show her that she should not feel sorry for surviving. Try to show her that a loving god (not the monster from the bible) would be rather happy that she survived as should all her friends in the congregation.
Don't fight the disassociation by action. Take it as an opportunity to leave and an example of their disgusting rules.