If you're searching for Marika's location in Kingdom Come: Deliverance 2, you must have started the Miri Fajta quest, which sees you searching for the Voivode's missing daughter. The leader of the Nomad Camp tells you that Marika disappeared without a trace, so it falls to you to do a little sleuthing and figure out where she's gone.
This is quite a long quest with a lot of travel involved, but working out Marika's exact location is definitely the hardest part. I've also included details about where to find Gejza's favorite spot, which is a later location-based quest step that's similarly frustrating.
Marika location in Kingdom Come: Deliverance 2
You can find Marika in Apollonia—the rocky, cave-filled region in the east of the map—but even knowing that she's still pretty difficult to locate. After the Voivode in the Nomad Camp tasks you with finding his daughter, you can speak to Herbwoman Bozhena from the start of the game, who'll tell you where she went and give you a rough search area.
The map screen above shows her exact location in a cave in the north of the region, but what you're searching for specifically is a small ravine with a trail of bloody rags leading into it from both the north and south. If coming from the south, look to your right immediately as you enter and you'll spy a little ledge with bloody markings on the walls and more rags—this leads into Marika's cave. If you're coming from the north you'll need to travel through the ravine a bit then look to your left instead.
After this you'll find Marika and can continue the quest, learning the truth about the situation with her father.
Where to find Gejza's favorite spot
The rest of the quest is pretty self-explanatory; the Voivode asks you to recover the nomad letter of safe conduct that Marika stole, while Marika asks you to acquire her father's protective amulet. The only tricky part comes when you have to rescue Marika's brother, Tibor, from Semine, and recover the body of her other brother, Gejza, where it's tied to a tree by a nearby woodcutter's camp.
The woodcutters won't be too happy about you taking it—they were the ones who killed Gejza—but once you do, you have to bring the body to his favorite spot for burial. The only problem is Tibor's instructions are pretty vague, so you'll find yourself wandering through the woods at a snail's pace because of the body on your back while searching for it.
Instead, use the map screen above and head to this location to the west of the woodcutters, along the cliff edge in the woods, where you'll find Tibor and the Voidvode's family waiting.
