It does, however, depend on the dealings with the land since her death.
It may be unregistered if she owned it for a long time or may not have been dealt with according to her will/intestacy provisions as yet.
If there has been no assent or sale or such then it may still be unregistered or registered in her name.
If this is the case and if a grant of probate or similar has been made (there is no time limit) you can obtain a copy and a copy of the will if any from the probate registry which may detail who the house was left to or who it is now vested in.
Try here for more details...
http://www.hmcourts-service.gov.uk/cms/1226.ht m#details.
If she does not have any surviving family etc... and died intestate the land would vest in the state (bona vacantia -
http://www.bonavacantia.gov.uk/default.asp?pag eid=1311) and would be dealt with by either the Treasury solicitors or solicitors for the Duchies of Lancaster and Cornwall (Farrer & Co in London)
There are companies who can trace owners of unregistered land etc... if you have no joy at the land registry eg 1stlocate...http://www.1stlocate.co.uk/ownerless_land.htm but they do charge fees.
Further enquiries and information would, I suppose, depend on your reasons for wanting to know.
If you want any more details let me know.