Yes. Depending upon the language in your contract [lease/option] you may be able to cancel the contract by showing a bad title in the owner/lessor. For that you should obtain a current title report from a title LAWYER. Many leases contain a covenant of quiet enjoyment that might help in this case. Also I wonder whether there may have been a misrepresentation by owner/lessor that would allow you to cancel. You would be wise to take all your paperwork to a lawyer who does real estate law practice. Keep a written record of all run-ins with the angry neighbors, take photos/videos, and keep reporting crimes to law enforcement. You might also consider filing a civil lawsuit against angry neighbors. These cases are sometimes difficult. Good luck.
These comments do not constitute legal advice. They are general comments on the circumstances presented, and may not be applicable to your situation. For legal advice on which you may rely consult your own lawyer.