A quick method to complete this room is as follows. Each step takes place as soon as the villagers start moving toward the centre column.
When the villagers turn their back, immediately mine the north-western rubium and put it in the north-western vent, then hide behind the north-western wall where you started.
Mine the north-eastern rubium and hide behind the north-eastern wall.
Place the rubium in the north-eastern vent, then hide behind the north-eastern wall and mine the eastern rubium.
Place the rubium in the south vent and click the south minecart to crouch behind it. You'll need to be quick. A safer method is to split this step into two steps- first, hide behind the southern minecart. Wait, then place the rubium in the vent and run to the south-western wall.
Mine the south-western rubium and place it in the south-western vent. The villagers will now pass out.
If you talk to the parents of Kimberly, they are at the end of the cave (where you found them mining in the quest), they will ask you to fetch an item from the surface. The items that may be requested are listed below:
The player will receive 2 noted coal in exchange for the item. The requested item cannot be noted. By equipping leather boots and an iron hatchet, the player may bring 2 spades, hammers, tinderboxes and leather boots, and 3 of each other item, and an extra of the item last requested. This will generally yield 30-36 coal per trip. However, as it takes several minutes to reach Kimberly from the south-east bank in Ardougne, players may find it more worthwhile to simply mine coal.