Nominated Successor

Hello, Mr. X is a husband of Mrs. Y & A, B, C and D are children of X and Y. Mr. X purchased a house (in 1992) from govt. development authority in UP. and Mr. X nominated successor(namit uttaradhikari) to his wife Mrs. Y (in the application form of registration, of development authority) Now Mr. X passed away in 2001. my query is 1) Is Mrs. Y sole legally successor or not? 2) what is the legal status of nominated successor (as above)? 3) how will Mrs. Y to be transfered the above property? Please sent e-mail as below prakash78857885@gmail.com