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"Ghost Appeaser", in which you appeased an angry ghost. (Quest level 4)
Get the shovel from the stables, go to the cemetery and 'dig in Isabel's grave with shovel'. Isabel's ghost will rise and haunt you. Go to the old house and search at the porch to get a key. Go inside to the kitchen and take the jar, then go to the parlour. Move sheet, move chair, move rug, go down and search. Head back to the cemetery and plant the seed in the jar. Drop the jar, because it will shatter in a few minutes. Take the rose and put it on Isabel's grave.