Should I avoid meat broth when cooking for vegetarians?

People choose to eat vegetarian diets for a number of reasons. Not only might the flavor offend your guest, but it may cause them to be physically ill.

You can substitute vegetable stock or broth for the meat products you are accustomed to using.

Mushrooms lend a meaty flavor to dishes they are used in and could potentially be used to replace your meat. I would suggest cooking them separately first to draw out the moisture, then adding them to the beans near the end of the cooking process so they soak up some of the flavors and have a chance to marry. Remember mushrooms are little culinary sponges. They will take flavors and run with them, adding their own earthy notes in the process. Search for vegetarian rice and beans dishes to get an idea of the possibilities here.

From an etiquette standpoint, you may want to avoid the temptation to apologize to your other guests for having to make a veggie substitution as that would be a quick ticket towards alienating your vegetarian pal. I only mention that because some people don't think about things like that and I have a few friends who are on restrictive diets. They are sometimes embarrassed when people go out of their way to make menu changes for them.

Another alternative altogether is to find a way to prepare two versions of the dish. Meaning, you could use meat as you are accustomed to but leave a portion of the food vegetarian. When it's practical I like this option a lot. It just comes with the downside of increased cleanup and stovetop logistics issues.

The answer to this is yes: avoid meat-based broth. From a dietary perspective, meat is unsettling to the stomach of a long-time vegetarian, and quite possibly repulsive, and the fact that it's broth (and thus, perhaps, "not really meat") is not the kind of call you want to make on behalf of someone who defines their own dietary restriction.

I have had personal experience with this from two angles: first, I once cooked for a vegetarian friend and had the foresight to ask this question of her, and she thanked me for it, because she had had to refuse food in the past because someone figured "it's just broth; that's okay, right?" It was not okay. And second, my family now includes several long-time vegetarians who say that meat is, at best, weird, and sometimes nauseating just to smell.

Occasionally I do make food that ought to taste like meat, which I try to mock up with particularly savory spices. A small amount of hot spicy Hungarian paprika is surprisingly effective at conveying the main aspect of meat's taste, at least in a soup where the main flavor is supposed to be something else. I imagine it would work with a beans and rice dish. I would agree with Preston Fitzgerald's suggestion of mushrooms, too; even better, if you can use a mushroom broth, since despite optimistic claims, mushrooms themselves are not a good substitute for the tactile experience of meat. Add a little extra saltiness to enhance these flavors (but not to the point of making the dish actually very salty, of course, and since you mention dietary restrictions, that's another one to watch for).

Edit: An update on the subject of the meat smell: there now exists a substitute meat product called "Beyond Meat", which makes hamburgers that I, as a relatively recent pescatarian, find to taste almost exactly like actual hamburgers. They also smell pretty similar, though not the same. My wife, who has the aforementioned meat revulsion, says that the smell is "borderline", though fortunately on the edible side of the border.

Many people avoid meat on moral grounds; many others avoid certain types of meat on religious grounds. You could risk really offending someone.

If you want to add that meaty background taste you can try soy sauce, but sparingly, and maybe add less salt.

Vegetarians do not eat meat or things made from meat. Meat stock is made from meat. Do not put it in food for vegetarians. End of.

While some vegetarians wouldn't mind, most would so you are better off avoiding any meat. There are probably vegetarian stock options which you could use instead, I'd recommend using those to be sure.

If it were me I would look to add depth of flavor in vegetarian acceptable ways. Caramelization of sugars is a good way and can be achieved by sauteeing or roasting vegetable, and perhaps frying the rice before cooking.