Mother deceased

My widowed mother passed away earlier this year and left no will.  I have two sisters and one of my sisters and I together with my mother bought a house as tenants in common 11 years ago. We are unsure of what forms we need to fill in and whether all three of us would need to be on the deeds as my other sister does not wish to own the house. Your help in this would be appreciated.

Andrea - sorry to read of your loss. If I’ve understood correctly then the property is registered in three names so the legal ownership passes to the two surviving owners to deal with as appropriate. 
If that means you both want to change and transfer the legal ownership then our online guidance explains how to do that - just answer the Qs to find the guidance and forms that applies to your circumstances 
If you remain unsure then share the title number and confirm who the legal owner(s) are going to be