House property

Mr X has written a will in 1998 for his house property (acquired from own funds). As per will, after the death of Mr X, the property can be enjoyed by Mrs Y through out her life time and after her death, the property will be owned by Mrs Z. Mr X died in 2005. After the death of Mr X, the ownership name has been changed to Mrs Y in Municipal Records and Mrs Y is enjoying the property. Mr X does not related to Mrs Y or Mrs Z. (Mr X had two daughters and wife, out of which wife and one daughter (married having children) died and other daughter (married) is alive). Mrs. Y (married but husband died and no children) (Children of husbands brother are alive). Mrs Y and Mrs Z are not related. Mrs Z was brought up jointly by Mr. X and Mrs. Z as parents of Mrs Z expired at her early age. Query : Whether the house property will directly can be transferred to Mrs Z after the death of Mrs. Y or Mrs Y has to write a will for transfer of property to Mrs. Z after the death of Mrs. Y.