My grandpa burn a little on foot and he also have diabetes, but wound doesn't so any sign of recovery. Can u suggest me which medicine is best.?

Burn. Your Grandpa has to keep going to his doctor until the burn is resolved. Recovery from a burn is essential if it can be done. Grandpa may need to lose his toe but I hope that is not necessary. If his diabetes is under control that's great. If not he needs more care.