媽媽有層樓留給我,

物業轉名須由律師辦理「送贈契」的手續。基於轉名涉及利益轉讓， 即使並沒有錢銀上的轇轕， 但仍要支付釐印費。 釐印費是按照稅務局的評估而定 ， 整個過程大約需時一個月左右。

Sorry for your loss first.

(Based on the following question you asked, I have to assume that your mother has been deceased:

https://hk.knowledge.yahoo.com/question/question?qid=7014053100101)

You will have to follow the process at here:

http://www.judiciary.gov.hk/tc/crt_services/pphlt/html/probate.htm

In this case, I will suggest you to find a lawyer. Once the probate is completed, the court will issue an order allowing the inheritance. But you will still need a lawyer to take care of all the legal document for the transfer.