If the new CIC checklist for Pakistan applicants requests for 12 months' bank statements then you'll have to provide the same.
Did your mom give the money to her relative as a bank transfer or she issued a cheque in the name of the relative? Also, how did her relative repay the money? If it was through bank transfers/cheques then you can provide bank statements + highlight these transactions to substantiate her claims.... and mention this in the 'Funds for visit' explanation.
If these were cash transactions then you'll have to provide some other evidence so that it does not appear that the money was recently deposited in her account for the purpose of the visa.... even though it is her money