Hi.. I am an allopathic doctor, can't comment on other sciences. According to the case you have presented, your child is having profound hearing loss since birth, she needs a cochlear implant surgery. Since, she's not hearing anything she hasn't learned speech yet, hence the mutism. According to the BERA report you have said, she will not be benefitting from hearing aid as well, hence the surgery.
Next Steps
consult a cochlear implant surgeon/neurotologist in your area and get it done soon.
Health Tips
there are various government programs that assist parents like you for the surgery. also, get this surgery soon, the earlier the operation, the better are the results. this surgery is not advocated once the patient crosses the 5 year mark.