It can be really difficult to determine the year without seeing it on a dress form or person, in order to determine the lines. It appears to be late 1880s-early 1890s or maybe late 1890s, but again I cannot tell with it on the hanger like that. I am trying to see the shoulder line, and it may be 1900 ish.
The hat is nice! Again it is hard without seeing it placed on a head or handling it in person, but it looks late 1880s to mid 1890s.
Not to burst your friend's balloon but the dress is rather boring looking, plus a dull color and very plain fabric. Collectors today are looking for fancier fabrics and styles, elaborate trims, or more unusual colors. I do love the buttons and if the price was right I would buy it for the buttons alone. The buttons are from the Aesthetic period, I would say 1870s 1880s. Hard to say if they are original to the garment.
