Upvote:-1
Yes she can. I also believe that you can request a "special need" aid to help her (if she can not go by herself). Embassies and consulates are accommodating to older people and those with special needs/conditions.
Upvote:10
Yes, your grandmother may be accompanied by someone for the interview process; as long as you inform the embassy in advance. From the embassy of the United States in Kuwait's website:
Applicants with physical disabilities: Applicants with a physical disability may bring an escort. Those requiring special accommodation should notify the Embassy of their needs well in advance of the interview date.
Note that even though this is from the Kuwait website, the information is the same for all US consulates abroad, since the website is actually managed by the State Department.