Trying to match up 2 columns of data on a partial match

I'm an excel noob, been googling for hours... surrendering to this forum.

Column A (will always be the same list)

aaaa.com
bbbb.com
cccc.com
dddd.com

Column B (different everytime)

cccc.com/excel-help
aaaa.com/i-use-excel-2007
dddd.com/sub-url

Column C (my ideal result)

aaaa.com/i-use-excel-2007
(left blank cause no match related to bbbb.com)
cccc.com/excel-help
dddd.com/sub-url



Tried uploading a sample spreadsheet but I got some kind of error.

Any help / advice greatly appreciated!

Thanks!