I am a maternal grandmother with guardianship of my daughter due to her low IQ and mental health. She had a child which I am also guardian of. If she is unwilling to sign away her rights to said child how should I proceed? I am concerned that should something happen to me she would regain custody/ guardianship of the child which is unsafe.
You've got a guardianship of the child which is all the law allows. People can't just "sign away their rights", particularly if they're mentally impaired. I suggest you contact an attorney who deals with guardianships and see what can be done.