She is hidding inside the catacombs. At exactly the middle of the catacombs is a small little hole in the floor. Click on it to see a close up view. Drag the rune stone to the hole, this will make the hole bigger. Make sure you have the following before proceeding: ceremonial dagger, scroll of spiritual mastery, and the crusader's sword. Go down the hole and you will find Emelda draining your life force, so better act fast. First you must drag the crusader's sword to the pentagram to weaken Emelda. Then use the scroll of spiritual mastery to weaken her further. Then use the ceremonial dagger to go for the kill. With this you have completed the game. Congratulation!