The Prophet (PBUH) said; "I am the last of the Prophets and my mosque is the last of the mosques." (Sahih Muslim. Hadith 2471)
Here I give a quotation from a Qadiani (Ahmadi) site to help you understand how they make a futile attempt to seek evidence in this narration for their false belief. They write;
--"It is clear that the Holy Prophet did not mean that there was to be no prophet after him, otherwise we shall have to conclude that he did not want the Muslims to build any other mosques. Obviously, what he means is that the religion brought by him is perfect and no one can cancel or modify it after him."--
Anyone who has the basic understanding of the Hadith and who looks at the complete Hadith will be able to get the twist and expose the lie. Infact this can be answered in many ways but a direct answer is found in another narration:
Holy Prophet (PBUH) said; "I am the last of the Prophets and my mosque is the last of the mosques of the prophets." (Kanz al-Ummal 12/270 H.34999. Albani authenticated in Sahih Targheeb wa Tarheeb H. 1175)
This indeed kills the Qadiani argument and makes it clear beyond all doubt that Holy Prophet (PBUH) only conveyed that his mosque will be the last of the mosques of the Prophets further supporting the Islamic belief against the Qadiani belief. 'Last mosque of the prophets' means there won't be any other prophet now because its impossible that a prophet comes and he does not build a mosque.
INDEED ALLAH KNOWS THE BEST!