Q: MacBook Pro - 2011 Model - OS X Yosemite (V10.10.5) :: Not able to use airdorp

Maybe this will help:

(How to) Use AirDrop to wirelessly share content

Mac Basics- AirDrop lets you send files from your Mac to nearby Macs and iOS devices

"not able to see the option seach older macs"

Macs must be running v10 Yosemite in order to use AirDrop >  Share content with AirDrop from your iPhone, iPad, or iPod touch

update to 10.10.5

if you want that your Mac works better with AirDrop add BT 4.0 USB as bonus you will get functional Continuity

get BT 4.0 USB based on Broadcom BCM20702 and download and install Continuity activation tool

https://github.com/dokterdok/Continuity-Activation-Tool/