Telling her off won't work.... in fact it probably reinforces the behaviour...
It is most likely that she is barking because she is nervous (or warning you of a threat). What you need is a good "quiet" command - perfect this away from the triggers before attempting it near her triggers... we had a similar issue with people coming to the door (and men entering the house)... when out Honey started barking at first I got up quietly stood between her and the object of her barking with my hand out behind me... after a while she would quieten down fairly quickly (we would then praise her for the quiet behaviour) - once she was quietening quickly I introduced a "hush" command with the body position and hand signal.. Now we normally only needs a hand signal and hush (I don't need to get up!) though if the perceived threat is big, I still sometimes need to stand between her and it... it's still a work in progress, but she's at least stopped trying to kill the post!!!!
The other thing which might help is to reduce her fear of these triggers.... get to a point where she can see one of these triggers but before she reacts and reward calm behaviour... gradually do this closer and closer to the trigger, but never getting to the point where she feels she needs to react. Don't push it, and (once you are close enough) allow her to approach the person (if they are willing) in her own time... once she is happy to approach them, she may accept food from them (but only do this once she is happy in their proximity) - at first they may need to drop it on the floor rather than feed her directly.
People with disabilities is a tough one, as there are so many disabilities, and they do affect how people move, interact etc. We thought we'd done so well with Honey introducing her to different disabilities - as a pup she visited my old work which included 3 people in very different styles of wheelchair, and people with other mobility impairments.... she saw people with walking sticks and frames too... however she had never seen people actually walking with either walking sticks or frames, and she panicked when she saw these strange contraptions actually moving!!!
Hope all this makes sense.... my brain is a bit fuddled lately...