Translation:The father is here to see his baby.
the subjunctive mood is the same as the indicative in english for most verbs (i.e. not "to be" "to have" and their ilk;) ) except in the third person singular where you drop the "s"
so technically it is only correct ( though pedantic) if you say "the father is there so that he see his baby" ????
although as Raul_Duke said I think if that is what you wrote it was most likely marked incorrectly because of the "that that"