what should i have done in this situation?

[Reforged]

yesterday i was on my laptop on a bench in a park like area, and this old lady comes up to me and screams "THATS MY DAUGHTERS LAPTOP YOU PUT THAT DOWN YOU THIEF!!" and it got real scary quick cus then everyone around was looking at this brown guy being accused by this white lady of stealing a macbook (i guess maybe they all look the same and she thought it was her daughters laptop? or maybe she was trying to steal mine that way?) but i got super nervous and for a second i almost gave it to her, but then im like NO! this is mine! get away from me.

and then some other people started walking my way and it got really scary i didnt know what to do. but i kept saying its mine and eventually she just walked away and said she would call  the police. :S

what should i have done in that situation? i have social anxiety and when i get thrown in situations like that it just really drives me insane.

Sounds like an old con woman looking for an easy mark. Confusion puts people into a more malleable state and embarrassment mixed with peer pressure would easily coerce someone to give up their prized possessions. When she realized it wasn't working she used calling the police as a reason to escape without alerting suspicion. If she was really calling the police she would of just used a mobile. 
Fight fire with fire. "Do you even have a daughter? Stay right there while I call the police, you can tell your story to them." Of course its hard to think with that much clarity in the moment which is exactly what she was counting on.