The divorce charges depends on case by case and regarding the time needed to finalize a divorce also varies, is it contested or uncontested divorce and etc?
Why don't you call a few lawyers to clear your doubts and know what are your mummy's rights?
This law office offers free phone consultation. Take advantage of it to understand how to help your mummy.
Their legal executive, Elin is very patient and understanding.
If you want to help your mother, there is an interesting article singaporedivorcelawyer.com.sg/silver-years-divorce-in-singapore-a-familys-journey/. The charges depend on whether your parents agree on the terms of the divorce. For example, the division of matrimonial home and other assets, also, if your mum is a stay-at-home, will she be needing maintenance.