When I went to Heartwood Mill and talked to Grosta about her husband's (Leifnarr's) murder, there was no option to tell her about his death. How do I fix this?
You might want to try the following as recommended by the elderscroll.wiki
Please reload an old save to confirm if the bug is still happening. If the bug is still occurring, please post the bug report with the appropriate system template 360 / XB1 , PS3 / PS4 , PC / MAC , depending on which platform(s) the bug has been encountered on. Be descriptive when listing the bug and fixes, but avoid having conversations in the description and/or using first-person-anecdotes: such discussions belong on the appropriate forum board.
PC This is a commonly broken objective and Grosta's state seems to be bugged. Current details are not known about the true quest flow for the object, but Leifnarr's corpse can be found in a secret room at Broken Helm Hollow. The corpse is an unnamed Nord and will give the one the objective to report Leiffnar's death to his family. Talking to either Grosta or Gralnach about finding him is not an option. Activating the quest before anything else usually prevents this bug.
PC(Fix) Enter CompleteAllObjectives 000E3EA5 into the console command. This forces the quest to be completed.
PC(Fix) Enter SetStage E3EA5 30 into the console command for Grosta. This will set her to correct state and allow notification of his death.