(Rain)))))))))))))) i think i agree with everyone intervention sounds like it is more than needed. Sounds like your friend was crying out for help.
She needs it imo
Such a hard spot for you ,, but you are helping the little girl and the mom
You said the daughter is 5 years old and deaf and autistic. I can almost say with 100% that little girl can read lips. I know she feels the spankyings.
My son at that age read lips. They thought he was deaf too.

I think the Mom needs help and forsure the child. As with all thats going on with her
this will harm her lots. It would a child with no issues imo