Use this code to create a grand staff in Lilypond.
<score lang="lilypond">
\relative c'' {
\new StaffGroup << % needed to show the brace on the left
\new Staff { \clef "treble" <c bes g e>1 } % some sample notes
\new Staff { \clef "bass" <c, g c, c,>1 }
>>
}
</score>