what should i do ? it said on I751 form lease on both name require, but we don't have to have lease agreement of our apartment we just pay monthly.
thank you

See if your landlord will provide you with a notarized letter stating that both (list both nanes) reside at such and such address, have resided there together since such and such a date, and are on a month to month verbal lease,then sign it listing him/herself as landlord and date it. That may help.

It is not required. It is one example of bonafides of marriage. If you don't have it, your application will be adjudicated based on the other bonafides you present.

We also got RFE last week mentioning rent agreement

we live with my husband's grandma and she owns the house,

1) would it help if she signed a notarised letter stating that we lived with her, paid part of bills and took care of her (she is 80 y o and otherwise would have nobody to do house errands for her)?
2) none of utility bills are on our names (except cellphones), but some payments were made by our checks, would it make sense to send copies of such cleared checks from our bank's website?
3) would it be a proof of residence if we sent copies of credit card statements for joint cards showing same billing address?

Tayoff, do you have copies of the cashed rent checks from your bank? That could be used to show residence.

If you don't have a lease don't worry... I'm sure there's other evidence you can provide, like a letter from your landlord or the complex manager saying that you've both lived there for X amount of time. A lease is just a piece of paper really...