If your father is looking for a courtroom brawl, the only way your mother is going to avoid a fight is to roll over and give him pretty much everything he wants. If, despite his choice of lawyer, he's willing to settle for half, it should be relatively easy -- he can instruct his lawyer to settle for an equal split.
Your mother would be well served to respond within the 30 days, and to hire a lawyer within that time frame. It is possible to move for additional time, but your mother would have to figure out how to prepare, file, notice and serve the motion -- and the court may say "no". She can ask her husband's lawyer to agree to give her more time, but he may say "no".
If they have been separated for five years, their estates will already be largely separate. Is this about more than equity in the marital home? e.g. division of retirement accounts or benefits?

