Water access through agricultural land

Good evening. As a favour, my father allowed through verbal agreement water access through his farm to the plaintiff about 10 years ago. Plaintiff used the access to transport water to his own farm for two to three years. Since about 2017, plaintiff has not used the access. My father passed away in 2019 and my mother is the new owner. The plaintiff is now demanding title of the land of water access from the new owner based on the previous owner's verbal agreement. My mother is agreeing to let the access continue, but the plaintiff wants her to pass ownership of the access land. 1. What is the legal validity of a verbal agreement with no evidence? What kind of prescriptive rights does the plaintiff have? 2. How many years does it take for prescriptive rights to start? 3. Did the plaintiff give up his prescriptive rights, if any, when he stopped using the access? 4. Is there a law that says any new owner has to comply with the previous owner's verbal agreement? 5. What is the need to give ownership if plaintiff is continuing to get access? 6. What is the guarantee that the plaintiff will use the access after getting title when he hasn't used it for 7 to 8 years? The only real result will be to drastically reduce the land value.