I was facing the same problem my wifi option was not coming , then I googled and found this solution you need to just execute these commands and your problem will be solved.
Note: Before executing these command you need to connect to the internet you can connect via LAN cable ,LAN was working in my case may be your LAN would also work.
There are no. of commands which you can try one by one.
sudo apt-get update && sudo apt-get upgrade
Now restart your machine. Done!!! check your wifi now.
if not worked go for 2
sudo apt-get install linux linux-headers-generic kernel-package
sudo apt-get install --reinstall bcmwl* firmware-b43-lpphy-installer b43-fwcutter
Now restart again , problem should be solved.
In case it also wouldn't work , try this final command
sudo apt-get remove bcmwl-kernel-source
sudo apt-get install firmware-b43-installer b43-fwcutter
Now check your wifi , It should work now... BTW my problem was resolved by 1. and 2. command only.