My aunt's property was left to either a friend or the church, can I contest successfully? Note: I am the only living heir.

If it was on a will, most likely not, people are free to leave things to who they want, but you can check with probate court, get a copy of the will and hire an attorney to file a motion to over turn the will.

My aunt's property was left to either a friend or the church, can I contest successfully? Note: I am the only living heir.
She had a living trust which we haven't seen yet, but appears that she left everything to her neighbor. Can I contest the 'trust'?