This quest is available after reading a book given to you by Keira Metz at the end of Wandering in the Dark. This quest is related to the Family Matters questline and will need to be completed in order for Family Matters to be completed.
DECISION POINT: Distracting Gran
OPTION # 1: Play hide and go seek with the Children Pretty self explanatory. Definitely a fun choice if you like watching Geralt play games.
OPTION #2: Give the children Candy The easiest option and moves along this section of the story much quicker.
GAMER TIP: When you help Johnny get his voice back DO NOT sell the Raven feather you will need it to complete The Whispering Hollock if you choose to save the tree spirit.
To complete this quest you need to finish The Whispering Hillock Quest

Embark on an inspiring mission of human connection beyond the UCA. Sam — with companions by his side — sets out on a new journey to save humanity from extinction. Join them as they traverse a world beset by otherworldly enemies, obstacles and a haunting question: should we have connected?