What is best way to avoid future property disputes legally?

A widow mother wants to prepare legal documents to ensure her self-acquired property (a house) goes to her son after her death, while giving a one-time settlement amount to her daughter now, along with a declaration that the daughter will not claim any rights to the property in the future. She prefers a will for the son but is unsure how to legally safeguard against future claims from the daughter. A gift deed is not preferred due to security reasons. What is the best legal way to do this?