What is Beowulf trying to say when he tells Wiglaf, "You're the last of all our farflung family"?
The epic poem Beowulf ends with Beowulf handing over his crown (his collar and ring) to Wiglaf. While doing this, Beowulf states (in the text I work from):
“You are the last remnant of our race and of the Wægmunding name, for Fate has swept all of my line, those princes of glory, into the land of doom. I must follow them.”
Here, Beowulf is trying to say two things.
First, there is no one who Beowulf would rather see take the crown. Outside of Wiglaf, none of his men stood by him as they promised. Wiglaf was the only man who stayed by Beowulf's side. Wiglaf was the only man who kept his battle-boast (promise) when it came to standing up for and by Beowulf. Therefore, the only person who Beowulf can see to take over his kingdom is the one man who kept his word (being, also, the only man who possesses the characteristics of a true hero).
Second, Beowulf has no family. All of his family (blood family) has been taken by fate (or by God, given only God makes the decisions on who lives and who dies). Beowulf sees Wiglaf as his family given he has been the one to always stand by him.
As for the version you are using, typical to the warriors of the epic, men travelled far (given the setting of the epic was vast) to battle for land, fight epic foes, and travel the world. Beowulf's "farflung family" is spread out among the vast lands. Given he is dying, Beowulf does not have the time to find them to name one king. Instead, he feels that Wiglaf is the last of his family who is still near. While not blood, Wiglaf has proven himself to be a true part of Beowulf's "family" by standing true and honorable.