No. Wills must be properly witnessed by two (2) independent witnesses. One of those witnesses can be the attorney draftsman. Most Wills today, prepared by lawyers, have a self proving affidavit attached. That affidavit is executed at the same time the Will is executed. It thus, avoids the necessity of tracking down witnesses after the testator dies, because the witnesses have already attested to the proper execution of the Will. That affidavit, in order to be accepted by the Court, must be properly notarized.
To expand on the prior response, the attorney and other witness must be "disinterested" witnesses, meaning they cannot be beneficiaries under the will that they are witnessing. But the signature of your grandmother does NOT have to be notarized. And the witnesses can either sign affidavits or appear in court to testify that the Will was properly executed and witnessed.