I can't find those people in Sweden with the limited information you provided but I can find Charles A. Hagerström returning to the U.S. from a visit to Sweden. The ship manifest at that time period should provide his last destination in Sweden, which should be a great clue to use to find more.
Emihamn was made from registrations with Swedish port police before leaving Sweden. (Not all Swedes left through a Swedish port.)
First name: CHARLES A Last name: HAGERSTRÖM Age: 81Gender: M Parish: AMERIKACounty: US Port: GÖTEBORG Date: 1910 08 19 Destination: PLATTSMOUTH Fellows: NEJ Source: 92:543:12238
Charles is an Americanization of Karl/Carl. Hagerström may very well be a name he took for himself after emigration. Many of our ancestors left Sweden with their patronymic name (a name ending with son or dotter) and only later took a surname.
Begin your search in the usual sources such as censuses, marriage *applications*, church records, death certificates, and so forth. Also use the marvelous archive called the Swenson Swedish Immigration Research Center. The Swenson Center has a website but its extensive collection of records is NOT online. We need to go there to research or pay them to research for us, but we are able to borrow their microfilmed Swedish American newspapers (which have obituaries!) from the Swenson Center. (They don't lend anything else.) It has records which are difficult or even impossible to find elswhere. Many of us have solved our most difficult problems there, such as where our ancestors came from in Sweden.