composition schem

Yes you can opt for the composition scheme. For opting composition scheme for the year 2017- 18 has been extended to 30th September,2017. Composition scheme will be effective from 1st October,2017.

yes u can do so.
but not for the July to Sept.

whether any notification issued regarding extension to composition scheme by 30.09.2017

Proposal at 21st GST Council meeting at Hyderabad

New time table for filing returns
1. GSTR-1 (for the month of July 2017) 10.10.2017
2. For registered persons with aggregate turnover in a state more than Rs. 100 crores., The due date for GSTR-1 for July 2017 will be 03.10.2017
3. GSTR-2 (for the month of July 2017) 31.10.2017
4. GSTR-3 (for the month of July 2017) 10.11.2017
5. GSTR-4 (for the quarter July-sep 2017) 18.10.2017
6. Table 4 under GSTR-4 not to be filed for the quarter july-september 2017. Requirement of filing GSTR-4 for this period to be dispensed with.
7. GSTR-6 (for the month of July 2017) 13.10.2017
8. Due dates for filing of the above-mentioned returns for subsequent periods shall be notified at a later date.
9. GSTR-3 B will continue to be filed till for the month of December 2017.

wether Composite delar is required to file GSTR 3B return and GSTR 1

No not applicable for composition dealer.

thn which form is applicable for those who optd composition scheme

GSTR-4 (on a quarterly basis) and GSTR-9A (Annual Return).

Yes you can do it so but not for the July to September quarter.