Airdrop - Do not see option. " Allow me to be discovered by ...."
Don't see option for Airdrop
See -> Use AirDrop to send files from your Mac to another nearby Mac or iOS device - Apple Support
If you do not see that option, it means that you have a Mac manufactured before 2012, so you cannot use that feature. You can only use AirDrop to share files to other Macs, but not to iPhones, iPads or iPods touch.