My Mom Locked My Dad Out Of His Savings Account

My parents have been unfortunately on the verge of divorce for a while now. A while ago my dad added my mom into his savings account, there’s over 100,000 in the account. A week ago my mom with no explanation removed my dad from the account, now keep in mind all the money in that savings account is my dads, every single penny of it is my dads, she put absolutely no money in that account. my dad is going to pursue legal action and unfortunately this is the last straw and they’re probably going to get divorced :( . If my dad decides to pursue legal action what can be done about this? I’m curious