In order to find out which broadcom card you have run this command and post the output.
lspci | grep -i network
Without Kali being installed on you Macbook; I'm not sure if installing the driver for your WiFi card will work.
I don't have much experience with Macbooks but I'll do my best to help you.
-::-Giving a title to your thread like " WiFi not working on Macbook running Kali" or something similar would have given your thread the attention it needs.-:-