Rotshen victor f hernando

Hello,my friend has an issue due to an entity called null they said that they saw null in there world multiple times,they said that they saw null in a cave minning diamonds,then they said that also saw null floating in the clouds and after it they said that their world crashed please help me cause they do not know how to contact mojang....they also said that they saw herobrine......I dont know if they are lying but please help me🙇🙏🙏🙏🙏