The fact that you refer to "the US Dept of Immigration" makes me think that you're not really on top of the documentation. I can't blame you, the bureaucracy can be bewilderingly complex. There are a variety of government agencies in the U.S. that deal with immigration, none called "the US Dept of Immigration". You're most likely refering to USCIS, DHS, CBP, or the U.S. Department of State depending on where exactly in the process your grandmother is. I recommend hiring a U.S. immigration lawyer and doing what they tell you. If you can't afford one, try fundraising, finding a pro-bono one or going to a low-income legal clinic.