Next step for SET(LR) dep?

[bluewaterlondon]

Hi If you can help me, bit confused.
got my ILR last year october ,2013.
My two kids got naturalisation done march 2014, applied for british passport.
My wife , who is living in the uk from june 2005, now her old visa will be expire 22nd september 2014( dependent of student visa).
also lost my job and im low income and getting child benifits, child tax credits, working tax credits, housing benifits and council tax reduction.

My question is:
what form i have to apply for my wife to extend her visa?
as im in benefits, what about maintenance, do i have to qualify for £18600.
or do i have any other way. please. thanks in advance.

[Amber]

FLR(FP). Then SET(LR) in June 2015 subject to eligibility.