Sponsorship details for visitor visa for my mother

[patilsanrsh]

Hi,

I am planning to apply for visitor visa for my mother in Jan 2014. My visa expires in May 2014 and extension is planned for it. My wife's H1 B visa expires in September 2016.
Considering my visa expiry date getting close, should the sponsor for my mother's visitor visa be me or my wife? Basically my wife should send the invitation letter for her or me?

Regards..

[immihelp]

It does not matter.