wine for the boyfriend's parental units

[wn]

I would like to purchase a wine for my boyfriend's parents. His father allowed me to intern in his lab for the summer and his mother had been incredibly hospitable during my time in a new city (helping me get an apartment, having me over for dinner, etc.) so I would very much like to thank them for their generosity. Unfortunately, I know nothing about wine. What is considered a "good" wine? Are there specific wines to purchase for specific occasions? I have no idea what their preferences are. My budget is $85. Please help!