You'd better take these documents with you（ ）you need them for t

You'd better take these documents with you（ ）you need them for the meeting. 

unless

in case

until

so that

本题考查连词。

unless：除非，除非在…情况下。in case：以备，以防；until：到…时，直到…为止；so that：因此，以便。

句意：你最好带上这些文件，以备开会时需要。

所以本题选B。