the main profession of ur sister is tution then file ITR-4
otherwise ITR-1 or 2 and income shown under the haed other sources in ITR-1 or 2.
Just want to add that if tution is profeession then use ITR-4S , if the Gross Receipts are 25 lacs or less...in such a case declare professional income as 8% of Gross Receipts......But if Tution Gross Rec exceeds Rs. 25 lacs then liable to Audit u/s 44AB and to use ITR-4.....