From friends on another board (I'll keep checking) this is all I've found out so far:
She was only 71 when she passed away.
Marie was outlived by her sister-in-law (Anna of Montenegro received monetarial help from Edwina Mountbatten): Franz Joseph (Padua 24 Sep 1861-Schaffhausen, Switzerland 31 Jul 1924); m.Cetinje 18 May 1897 Anna Pss of Montenegro (Cetinje 18 Aug 1874-Territet, Switzerland 22 Apr 1971)
children of Gustav, 1st Fürst und Graf zu Erbach-Schönberg by his wife Princess Marie von Battenberg (1852-1923)? She outlived her husband by 15 years. They had at least four children: Alexander, Maximilian, Victor and Elisabeth. She had one child who suffered from a severe mental handicap...and was very candid about it. This may have been Maximilian since he died at 14 and was the only one, I believe, without marriage/issue.