What to do with Wife’s 401k

My wife decided to quit her job this week and become a stay at home mom. Really excited for her to take this step as I make more than enough to support our family. She has a 401k with her former employer with just under $10k in the plan. What should she do with the funds? Ideally we would like to keep it in some sort of retirement fund that I can contribute to post-tax from my salary. What options should we be looking at?