Question

You'd better take these papers with you ________ you need them for your meeting.

Answer 1

as..... or, because can fit in..!
I think

Answer 2

There are two ways the blank can be filled. Two examples of words that can be used here are:

1. You'd better take these papers with you UNLESS you need them for your meeting.

Unless signifies here that the papers can be taken by a person if they are not required during the meeting and leaves the possibility that if they are, the person may leave the papers there.

2. You'd better take these papers with you IN CASE you need them for your meeting.

This possibility suggests that a person should carry the papers with them just in case, in a possibility that they may need it for the meeting.