To make this easy for you, here's where the buried socks of hers are located at.
1) Stand behind the brown pine tree behind the house and go one step up and one south of the brown pine tree. Stand on the 3 stumps and dig. Well there's one sock found!
2) The second one is located near the wagon area. There's a cluster of pine trees there, when you first get off the wagon. The first three pine trees dig in the middle of and you'll find the sock.
Yay found number two! Only 5 more to go!
3) Go south of the two logs in the forest and stand on the edge of it south if the single rock.
You found a sock! This one has an orange triangle embroidered on it. One more found! that makes three!
4) Go to the west a few paces and stand west of the double stumps by the twin pine trees and dig. You found Sock 4, YAY!
5) Go 10 paces west till you find a cluster that has three trees. Dig in the opening of the U shape that the trees make. There's sock 5
6) Now in the around same site as where you found number 5 go down where the three trees are below and dig on the right side of them. There's sock 6!
7) Stand directly south of Nina's house in the forest between two pine trees across from a log and dig. You found sock number 7!
Bring them back to Mandy. She's glad to have them back!
Reward: 8 Dino bones and 50 QP