I was told that "Can I lead you to the meeting room" should be changed to
"Can I show you to the meeting room/ Can I take you to the meeting room".
Is the verb 'lead' really not acceptable if I am really walking along with the person to the meeting room?
You can lead the way if you walk ahead of a group of people, and you can lead someone if you take their arm because they need assistance or restraint. In the situation you have described, 'show' and 'take' are more appropriate.