If the parties reside in different cities, barangay conciliation may be dispensed with. It is possible that they have moved to another city, that is why.
If your parents were aware that there was a tenant in the house when she bought the property or if the contract of Lease was registered at the Register of Deeds, you are bound by the terms of said contract. That means, you have to wait until the contract expires before you can remove the tenants therein. In other words, the Lease Contract follows whoever is the new owner.
Coercion happens when you force somebody to do something against his will. Oral Defamation is simply "Paninirang puri". Trespass to dwelling can be committed by the owner himself. Indeed, a mere tenant can charge the owner of "Trespass to dwelling". The issue here is not ownership per se but "legal possession". If the owner unlawfully entered the property, the tenant can charge the owner for said offense. Hence, in "Trespass to dwelling", ownership is not a defense.
"Fixation"? I think you are referring to "Unjust Vexation". It is committed when you disturb or irritate the "peace and tranquil living" of a person.