I would commend  Guilmant's Lamentations opus 45 #1. This was composed
in memory of a Army Chaplain who was killed during civil unrest in Paris. It
is based on the first eleven verses of Jeremiah's fifth Lamentation. It
starts with a gloomy opening melody , builds to a tension filled climax then
into a mood that is much relaxed, closing with a gorgeous harmonisation of
the Gregorian chant "Jerusalem,convert to the Lord thy God". In my view this
is so appropriate for  any service that is focussing on the life and passing
of Diana, Princess of Wales.
 
Hugh Drogemuller