Clearly she did not trust La Fayette -- and foolishly so -- despite the many proofs of his loyalty. He had saved her first from an angry mob by appearing together with her on the balcony of the palace at Versailles on October 6, 1789 and a second time when he lied that she and Louis had been "abducted" by "enemies of the revolution" during their flight to Varennes in June 1791.
What makes me say that that M-A desired death more than life was that despite the fact that she had narrowly escaped mob lynching just a few days before on June 20, 1792 in the Tuilleries, M-A still preferred death to any help from La Fayette, help which would have militarily restored the royal authority, albeit a constitutional, not absolute one.
Perhaps she was ready to die for her ideal of absolute monarchy when rejecting La Fayette's help for a constitutional monachy, but something makes me doubt that. She had two little children which would have had to die also together with their mother (the Dauphin did share her fate, not on a scaffold, but died nevertheless as result of purposeful neglect); however, no mother would sacrifice that much on the altar of any political idealism. That's why I think she was probably subconsciously desiring death for other reasons, not political, but for matters of the heart (such as missing Axel and/or Gabrielle)...