Very good deal for a single person who wants to save money while staying in Montreux area. The village of Rennaz is a 30 minute walk or 8 minute bus/car ride from Villeneuve, where you can take a trolleybus to Montreux. The bus schedule between Rennaz and Villeneuve is here (##111 and 115):
http://www.tpc.ch/index.php?option=com_wrapper&view=wrapper&Itemid=160

If you miss the last bus from Villeneuve, you'll have to take a taxi which is very expensive and very difficult to find.

Also, be aware that you will have to follow certain rules while staying with Elisabeth, such as cleaning the wall every time after you take the shower (to prevent build up of calcium), washing dishes, not using the kitchen after 10pm etc. She was very nice to pick us up from the train and give us a ride back to the train, but basically you're on your own. If you're OK with all that, than, like I said, it's a good deal.