May 3, 2016 - 11:46 PM
You may struggle finding something open at this time of year. A lot of the huts in the Oberland are quite high and don't open until June. As Slowpoke suggested, the Swiss Alpine Club site will have all the info you need. Something else to consider is how variable the weather is this time of year. It can snow heavily at the drop of hat, so you may need to be a bit flexible in your plans. If you can hang off unill 19th June, the Glecksteinhuette above Grindelwald will be open and it's well worth an overnight stay.
Have a safe trip.