How do you control, contain or whatever a person that continually wants to roam, may pick up a plate of food and dump it on the table or floor, uses bad language and is basically obnoxious. The individual should be institutionalized while other family members support the concept the wife says no, that she'll continue to deal with it.
What kind of help does the wife have?
Give us a little more information, for more specific responses.
She needs to talk to his neurologist to hear it directly on his outlook and what will come next. If he has not had a neurology work up, that is critical sooner than later. Different dementias progress different ways.
There is no magic little pill for these behaviors.
If you, or someone you know, is living with someone who has degenerative brain disease, educate yourself about it. Expecting someone with this problem to behave is no longer possible. They can't. It's not in their ability any more. It's not misbehavior like a little child would do. Their brain is changing.
Go to Youtube and search for Teepa Snow. She is a dementia educator who is very relatable for those of us who are not medical people. She role plays during her seminars and does a great imitation of my mother! There is a series called "making visits valuable" that will teach you a lot about why these behaviors are happening and how to understand them & respond so as not to frighten the person & make it worse.
If you can sit with the wife and help her watch these videos, it might make a huge difference in her thinking.
Take her to tour local residential facilities. It's not scary like the state mental hospital from 60 years ago. They are very cozy, homey, and try to be as comfortable as possible. They have different levels of care for people who are in the early stages vs. late stages.