Okay, I have just killed Argamir and have his Manifest and shovel in my inventory. I have returned to Jensine but for some reason I cannot give her the shovel or the manifest to receive my reward. What do I need to do?

Go see Thoronir first.

Mara

I have already seen Thoronir and he has given me ring.

Go back and talk to Jensine. Make sure you scroll down through all the dialogue options. Some are hidden from view unless you scroll down.