How abt helping her to start by juz waving to say hi?
I exposed my LOs to people by teaching them how to say hi via waving first, then slowly progress to saying hi. I will hold their hand and wave with them.
If they bury their faces, I’ll juz say “she’s shy la”. Then later go home slowly explain and teach. In the meantime, I’ll bring them out more often and expose them to more people and teach them that it’s safe to greet whenever mummy’s around cos these people are my friends. :)
Hope your LO overcomes her ‘fears’ soon. :)