Elderly neighbor friend lives alone. She spend lots of money having new locks put on due to her hallucination of break-ins. How do I help?

I am assuming there is no family or close friends you have observed?
Quite honestly you cannot help other than to try to get help and intervention.
She is delusional, and only diagnosis and a safe placement can help behaviors such as this. You should report this poor woman for Adult Protective Services wellness checks and let them know what you know. If there are locksmiths who you know to be willing to give you a one page write up about their experience with this woman that may help. It is then up to the state to contact family (if there is family) or to decide upon diagnosis, prognosis, safety, the possiblity of treatment. Thanks for being such a good neighbor. Do know that her living in a condo with this level of impairment also represents a danger (fire and many other things) to other members of the condo. Condo management should be informed by APS or by you if there are continuing problems. What a tragedy this is.

A homeowner (ok, a condo owner) has the right to change locks whenever he/she wants to. Plus the fact that she works speaks to her functionality. I was in this situation myself with a former next-door neighbor. There's nothing you can do but call APS (who won't do anything if she has food in the fridge) or the SPCA (who won't do anything if the dog is of normal weight and has food, water and shelter).

Does she have any family at all? I'd recommend contacting the police for a welfare check. They'll get Adult Protective Services involved.