Visiting Visa For In-Law


I am currently in US on a L1B visa and my husband is on L2 and had applied for his work permit, we have our visa's valid till Sept 2011.

I want to bring my mother in-law for 5 months, please let me whether it spossible? and the procedure to file for her visa. She is not working there but literate, and helping her husband in a christian ministry.