The track played when bonnie says she cannot attend the wedding and stefan hears it standing behind the door that track has come alot of times in the seasons 

We're Planning A June Wedding

Matt questions a witness at The Mystic Grill and his dad and mom arrive.

Secret Colours

Changes In Nature

Pins And Needles

Bonnie listens to music as Enzo appears to comment on her melancholy song choice.

Billie Holiday

I'm a Fool to Want You

Guests gather for the wedding; Matt asks his mom if she's seen Peter; Caroline coaches the kids on what to do in the wedding as Bonnie arrives.

Kodály Quartet

String Quartet No. 62 in C Major, Op. 76, No. 3, Hob. III:77, "Emperor": III. Menuetto

Alaric tells Dorian how losing people brough him together with others as family; Caroline walks down the aisle.

Lights & Motion

Silver Lining

Damien pronounces Stefan and Caroline 'husband and wife'; Caroline and Stefan kiss. 

Perfect Symmetry

Wedding reception; Bonnie dances with Damien and temporarily sees Enzo take his place; Matt's mother puts a propane canister in the fireplace; Matt leaves his mother a message, then follows his dad's ringtone to find him injured in a ditch.

Kaleb Jones

Till the World Stops Turning

Vicki starts ringing the Founder's bell; Bonnie collapses; Matt's mother coughs up more blood, then dies.