f2b petition lived only 2 months in usa.what happens?help plzzzz

[andre.nia]

Hi everybody.I am about to go for an interview,in a couple of weeks.My mom as my petitioner has only lived 2 months in the US.She entered US without any problem two months ago,came back after 3 weeks.I am planning to send her back to USA 2 weeks before my interview.She is 83yrs and suffering from diabetes and pschologycal problem as the consequence of her illness,that can be certified by physician.Have you any similar experience or knowledge that is there any problem in my interview?Ofcourse i must mention that in her recent trip to US,she collected some domicile papers like a bank account , registered electricity bill,phone bill , a medical record and medical insurance and some other.Will i face any problem at the time of interview?What will be that? and of vital importance to mention that in recent trip to US she obtained a Travel Document.