ANSWER:

The walima is your responsibility according to your ability and will. Having it in a masjid is not from the sunnah and there is no special thing, as you can’t also invite people to dine in the masjid. Therefore, you should have it home or in a public place within reason and without extravagance.

But if your in laws want something big, they should either share the expenses with you or pay for it themselves in a separate night of their own. 

QUESTION: Am about to get married in a few months. My in laws wants to have nikah in a function hall. Bt i want in a masjid. Bt they r insisting on function hall. What should I do sheikh? Is it okay to accept