Query on bank statement period for UK standard visitor visa

[ss2607]

Hello,

I am currently on a PBS dependent visa with my husband on Tier2 General. I am looking to sponsor my mother to visit me in the UK. The challenge I have is that her bank account was opened 2 months ago and as there is a requirement to submit 6 months of bank statements, I am concerned if she may not be eligible for the visa. My father passed away last year and his bank accounts are all closed and earlier too my mother did not have any bank account at all on her name. If anyone could please help me on any advise what can be done in this situation - like if 3 months bank statement is acceptable? Many thanks for the advice