Buried Treasure

The following story is not mine, but that of my grandmother's.

My grandmother lived in a small town in Mexico. The town was nestled in the middle of a valley, of which visitors can only come in by steep and dangerous paths.
The town served as a refugee camp for Germans during World War II and because of the difficulty of entering the town, it was infamous for having criminals come in to hide.
This story takes place at the end of the 1940's before my mother was born. My Grandparents were very poor and they lived in an old house. It was summertime and so they would sleep with the doors open for ventilation. One night my grandmother was woken by voices outside. She gathered herself up and took a look out the door. On her patio there were four men. Apparently they had built a fire and were conversing. My grandmother heard them mention that they had gold and they had just buried it. Frightened that there were people on her patio and that they may be criminals, she went inside to wake up my grandfather. He came rushing out but when they reached the patio there was nobody there. There were no footprints or any signs that anyone was ever there. Even the campfire was gone!! There were no ashes or pieces of wood to suggest that anything had been disturbed.
My grandmother had put the incident behind her and in a few months they had moved out of that home. New owners came in and started living in that house not knowing what my grandmother had witnessed. The new owners decided to remodel and repair the house. One day they were excavating, and they found the gold!!! Today their family is very wealthy because of the found gold. My grandmother always kicks herself for not trying to find the treasure that the four ghosts had mentioned, after all, it was her apparition.