Rescuing her.

It started to rain. To Oliver's dismay, the drizzle which had started a few minutes back has started to intensify.

It would have made the searching process more difficult however, while he was on his way to the mountain, Oliver contacted one of his friends who is a tech geek. 

He asked him to get the detailed, real time map of this mountain asap so that he could know where the river and the graveyard is.

While his friend was working on this, Oliver made a call to Anthony and just now, he finished the call. 

As the map could be found instantly, Oliver's friend sent him the very next moment he asked.

As requested, it is a real time map which his friend has directly accessed using a satellite. 

So, Oliver was able to find a way to Kyra's grandmother's tomb though it was raining.