You previously were able to follow Lilith’s tracks but reached a dead end when all you found was the body of Rathma and the key to Hell missing.
It seems that Lilith was able to obtain the key to Hell and will be using it for a bigger plot that you do not have any idea about yet.
Your next step is to meet Neyrelle to tell her what has happened and to see what she has been up to in your absence.
How To Get Light’s Resolve Quest?
You will receive the Light’s Resolve quest after you have completed the Descent quest, where you previously followed Lilith’s trail to the body of Rathma.
Light’s Resolve Quest Objectives
1) Speak with Neyrelle
After the previous events, you will need to meet up with Neyrelle and this can easily be done by teleporting first to Yelesna.
2) Speak with Neyrelle outside the Horadric Vault
Neyrelle will be outside of the Horadric Vault most likely tending to her mother’s body and you will need to head over there to speak with her.
You can proceed by making your way to the Mistral Woods and following the marked area to reach Neyrelle.
3) Speak with Neyrelle
Neyrelle will be standing in front of a gravestone, which will belong to her mother and you will need to speak with her to start a cutscene.
The two of you will talk as you hand her over the trinket that Vigo had told you to give her, which he accepted from her mother.
The cutscene shifts to a narration with Lorath speaking, giving a summary of the events as well as a hint of what is to come before the quest ends.
Light’s Resolve Quest Rewards
After the Light’s Resolve quest has finished, you will be rewarded with XP and Gold that is determined by your current level along with the Vhenard’s Esoteric Signet. (Rare Ring)
It looks like your initial pursuit of Lilith did not go well and this can be either because of the delay with the blessing or because Lilith was just too fast.
This is not the beginning though as there is still hope but the road that you need to tread is a mysterious one but you will still have allies that walk with you.
Your next step will be to find a man named Donan, a Horadrim that Lorath had previously told you to seek out before the two of you went your separate ways.