If older woman and new young husband, can she get tubes untied and have baby at 42?

Yes. But becoming pregnant may be difficult and will be considered high risk due to advanced maternal age. But it is possible to carry healthy baby to term.
Maybe. Sometimes the attempt to reconnect the tubes does not work well and may even make you prone to a life threatening tubal pregnancy. You may want to consult first with a fertility center and consider all your options. They could harvest your eggs and fertilize them with the spouses sperm before implanting the embryo in your womb. Either way you do have options.