I’m sorry to hear about your wife’s misfortunes. The following contains some information that may be of assistance. In particular, taking the spectrum of B Vitamins is crucial in stopping the progress of nerve damage, most especially Vitamins B-6 and B-12. If it were me, I would take what is called B-50 twice daily and additional supplements of B-6 and B-12. Although there is a product called B-100, it would not work as well as most of the vitamins would merely be flushed out of the body…too much at once.
https://www.earthclinic.com/cures/diabetic-neuropathy-treatment.html