There is nothing to stop them .,however we can stop this immigration who will vote for these people, and pushing their sharia. We can also look at many of these mosques , and where they are being funded from.
Any individual can do very little about immigration. You can vote for your Congressmen and Senators. At your state level, you might have choices that are less or more open to providing welfare benefits to immigrants.
We can “look at” funding for mosques, but what can we do about it?