Understanding "I am the last Prophet"

...it comes quite often that we do not understand: like Prophet Mohammad said that “I am the last prophet.” All right, He did say that He was the last prophet. Supposing I say, I am the last person to come here. All right I would say just to frighten you that you better take to it otherwise this is the last time I am telling you. But it is never that because when He died He found out that, you see, these people are mad cap. “I didn’t tell them this, what are they doing out of me?” So he said, “I better go back again,” and He came as Nanaka and He told them that “Hindu and Muslims are same people, following the same religion, why are you fighting among yourselves?” He came for that unity. Then as Nanaka He came; so in Nanaka’s system also the Sikhism came in and they started a warrior class and this and that. I mean imagine, the Sikhism ended up by having wars within Muslims and Hindus. So then He came as Shirdi Sai Nath to teach them. Now this is not a very important thing that, say Mohammad Sahib said, “I am the last.” Say He is the last, all right, even take that position. Who are you to him? How are you related? Through what? What is your authority? How do you appropriate Him to yourself? Because you say you are Muslims. So what? How did you become Muslims? Did you get your certificate from God?

H.H.Shri Mataji Nirmala Devi, extract from 'World of Bliss and Joy', talk at Caxton Hall, London, 30/5/79