fno losses offset

can Fno looses offset with other income like capital gains and income from rent ?

Yes it can be

under what all heads , it can be used to offset ?

Other than salary income business loss can offset against all other heads of income

is this apply for carry forward non-speculative losses also ?

My doubt is a loss on FNO(FY17-18) can be used to offset with other income in next financial year(FY 18-19) like LTCG , STCG or house rent ?

No , Carried forward loss can be adjusted against only fno income which is treated as speculative for carry forward. In the same year you can offset against other heads.