Hmmm, I wonder if your mom sent that sort of letter/care package to your other exJW siblings too. If she did, I'd definitely be getting the group together to confront her about the lie that "all but you" have returned to Jehovah.
Definitely discuss with your other exJW siblings about creating a pact to refuse further financial assistance to her. Let her congregation look after her, since she's chosen the Organization over her own flesh and blood.