Paris to Giverny Garden and then Bayeaux

Monet's garden then the Bayeaux tapestry are not connected by rail but you could rent a car to drive use google maps to search.
You could take the train or rent a car to Bayeux stay two nights one seeing the tapestry and the town and one so your husband can tour the D-DAY beaches.. Then drive to Giverny from Bayeux on the way back to Paris.

Or take separate day trip from Paris to cover Giverny. That can be easily done..

"I do not know if this is all doable in a long day?"
No, not really. As mentioned above, Vernon to Bayeux by train is not a direct connection. You would either need to go back to Paris or make two connections through Rouen and Caen. But even if you drove, from Paris, you cannot go to Giverny, Bayeux and the D-Day beaches in one day. If you decide to go by train only, I'd separate them and do an overnight trip to Bayeux -- early morning train followed by a visit to the Tapestry and then guided tour of the D-Day sites on day 2 followed by an evening train to Paris. Then, Giverny could be done as a day-trip from Paris.

If you rent a car and are very nimble you could visit (1) garden and (2) tapestry in a single day.

I think most people would prefer to take more time and see more of Normandy. For instance, Bayeux is charming, and the cathedral where the Tapestry originally hung is worth a visit. And there are the historical sites from the Normandy Invaision, and a lot more.

Traveling all that way and cherry-picking the tapestry is unusual, but to each her own. Get an early start.

A Norman trip that is feasible by train might be an AM visit to Giverny and an afternoon in Rouen, which has a fascinating and walkable old center.

Ahhh, very good advice, thank you!

I found the France rail site and am now getting a better sense of distances--and where the lines run.
I was thinking that if we rent a car, perhaps my husband could drop me off in Bayeaux and then go on to the beaches.
(I do love history and we watch many movies about WWII, but I think it would be too sad to go there, myself.
Ironic, since the Bayeaux Tapestry is also about war....
But I am an art history major....with a long list of art that I have always wanted to see!)

that is alright we 've all traveled with people and some days we go separate ways to get the most out of it

I think JHK's advice is perfect. Giverny one day by train, and Bayeux a separate trip by train with an overnight in Bayeux. Your husband can do the day tour and you can enjoy Bayeux.
You can do same by car instead of train (but train is quicker, stress-free, enjoyable and may be cheaper than renting a car + gas) but I'd stick with JHK's advice. Bayeux deserves at least 1 night, not a day trip, and not combined with Giverny.

While in Paris go to the Cluny Museum and see The Lady and The Unicorn Tapestries.

Museum has never been crowded while I've been there
And the tapestries are beautiful.

Thank you to all. You are so helpful.
I am going to take your advice and plan an overnight stay in Bayeaux.

Perhaps the Marmatton Museum and Giverny would make another day--it looks like the Museum is already on the far west side of Paris. And it is a combo ticket, and Rick Steve's guide says Giverny is less crowded later in the day....

And to the person who recommended the Cluny Museum, absolutely yes, I plan to go there, too!