After a recent Marriage there are two homes. When we sell one what is the smartest things / options to do with the profits. approx. 20-50k.
We are ages 44-groom and 31-bride.

The smartest thing to do with the profit is to save it in a secured investment such as a insured money market fund, CD, or a municipal bond.

It really depends on when you will need the money and what you will need it for. You should also consider whether or not you have an emergency fund in case you would become unable to work or lose your job.

I typically recommend that people set aside at least 3 months worth of expenses in FDIC insured CDs. For example, I would recommend that they buy one 3-month CD the first month, another 3-month CD the second month and a last 3-month CD the third month. That way they always have a CD maturing and will be able to access the money if they need it.

If you already have an emergency fund and have a specific goal in mind for the money, you should consider an investment that is appropriate.
If you have a goal within the next few years you want an investment that is fairly safe and protects the principal.

If your timeline is longer and you can accept a little more volatility then you can take on more risk and perhaps look at the growth or income producing investments.

In short there is no quick answer, you probably need a deeper analysis of your overall financial picture.