Levanger is the name of a clerical district in Nord-Trøndelag, Norway. The closest city/port for departure would have been Trondheim.
It would be helpful to have at least approximate birth years for these persons for searching the emigration database from that port... but I can at least try for the more unusual names in the family.
There is a man identifying himself as 'Abel Mo' who left from Trondheim in 1882 stating his age as 49, that he is married and his intended destination is "Sioux City Jowa" --
http://digitalarkivet.uib.no/cgi-win/webcens.exe?slag=visbas...Two young men who MIGHT be your family members leaving from Trondheim in 1888 -
http://digitalarkivet.uib.no/cgi-win/webcens.exe?slag=visbas...The couple Abel and Johanne living on the farm "Storborgmo*" in the 1865 Norwegian census -
http://digitalarkivet.uib.no/cgi-win/webcens.exe?slag=visbas...