A family friend came from a concentration camp to an uncle in America through efforts of the Red Cross. She arrived by ship in New York and then went to stay with her relatives. Perhaps your friend's grandmother also arrived in N.Y. (Ancestry, a subscription site, should show N.Y. arrivals).
If the grandmother was in a concentration camp it's quite possible that other members of her family were also in a camp but didn't survive. If that's the case she (or another relative) may have added them to the database of Holocaust victims on this site- heartbreaking to read but often lots of information on where the family came from, etc.
https://yvng.yadvashem.org/Feel free to PM me if you have any queries