\version "2.18.2"

upper = \relative c'' {
  \clef treble
  \key g \major
  \time 6/8
  \afterGrace <c fis>2.\fermata {s8 b16 ([c] d [c b a])} |
  \stemNeutral
  g4 
}

lower = \relative c {
  \clef treble
  \key g \major
  \time 6/8
  <d' a'>2.\fermata \clef bass |
  <g, b>4
  
}

\score {
  \new PianoStaff <<
    \new Staff = "upper" \upper
    \new Staff = "lower" \lower
  >>
 
}