Maintenance by hc

Yes. Possible. You can reduce by using CrPC 127.

Please read each of my posts carefully in the following links for sample petitions and other necessary clues.

https://www.lawyersclubindia.com/forum/Fight-against-misuse-of-498a-ipc--103100.asp#.U6gslUCm9dg

https://www.lawyersclubindia.com/forum/Best-way-to-fight-against-false-498a-103111.asp#.U6gsRkCm9dg

https://www.lawyersclubindia.com/forum/details.asp?mod_id=104564&offset=1

if the maintenance is decided already and now since your circumstances have changed you can apply for a modification suit

can the wife seek maintanance from motherin law and can she attach motherinlaw's absolute property 

Its your bad luck, the SC has now given absolute right to wives to extract maintenance at will:

https://www.lawyersclubindia.com/forum/Sc-alimony-not-for-mere-survival-119061.asp#.VSPCz9yUeSo

File petition u/s 127 Crpc for change in circumstances. However, your wife may quote this as this judgment refers to even husbands without any job. The SC says no matter if you are earning or not, if you have source or not, if you are healthy you have to arrange funds and pay it to wife for her luxory.

@kameshwaran no is the answer for both the questions