Wow.
Is there any other family who can help them out a little?
If family could help in any way... If your cousin could get a total of eight outfits (sleepers?) in each size, that should keep the twins clothed adequately. They won't have a lot of extra clothing, but that would give your cousin enough clothes to have an outfit on each baby, a spare or two for accidents, and one in the wash for each baby. They will be doing a lot of laundry, but their babies will have clothes.
Or, even if several family members could each give them $10-$20, they could buy some basics. Do they have a Salvation Army, Goodwill, or other consignment store around them? Sometimes you can get baby clothes for as cheap as $1-$3 per item. I know that is still a lot of money when you need everything in multiples of two, but it would at least give them a start.