PREFIX foaf: <http://xmlns.com/foaf/0.1/>
PREFIX vcard: <http://www.w3.org/2001/vcard-rdf/3.0#>
SELECT ?foafName ?mbox ?gname ?fname
WHERE
  {  ?x foaf:name ?foafName .
     OPTIONAL { ?x foaf:mbox ?mbox } .
     OPTIONAL {  ?x vcard:N ?vc .
                 ?vc vcard:Given ?gname .
                 OPTIONAL { ?vc vcard:Family ?fname }
              }
  }