Firstly, she should consult her obs/gyno doctor for ANY change in regards to diet or excercise. They are the only people she should really trust with this as they have the knowledge developed especially for this type of thing!!
She has to remember that she has special needs for her diet now so she should focus on providing things to the bub. The baby requires all of the vitamins and minerals, but especially things such as vitamin A, calcium and iron, and has a BIG need for omega 3 fatty acids as well (especially later when the brain is rapidly developing)!! These are all VITAL to making sure the babys growth is not disrupted. Other things such as folate and iron are also really important.
Also, although suppliments help with these, real food is MUCH better for getting vitamins and minerals as these provide them in combinations that hel absorption and they also provide phytochemicals which are essential for health. But, it is really hard to get all of the required vitamins and minerals needed for health when on a hypocaloric (low cal) diet, so make sure she is eating enough for herself and then enough for the bub as well. 5 to 6 meals a day is good as it will help keep her blood glucose stable, which is important during pregnancy.
I would think the multivitamin is good (and there are special pre-natal ones she can take), but she really should look to dropping most suppliments (esp. things like fat-burners), unless they have been 'ok'd' by her doctor.
Now, about the moderate carb... How moderate is moderate? The baby has an ABSOLUTE requirement for carbohydrates. This is because carbs are basically the only form of energy it can use at the moment. So you have to make sure your wife is getting enough starchy, low GI carbs - otherwise both baby (via stunted growth) and mum (via hypoglycaemia) will suffer. Low sugar yes, but low carb - not a good idea.
Protein level required for pregnancy is still in debate. I would think if she sticks to 1 to 1.2g of protein per pound then this will be more than adequate for her without being too high.
The things she should focus on are those things that are suggested for good health. So LOTS of fresh (and well washed) vegetables. You might want to make sure there are lots of dark-green leafy vegetables as these are packed with vitamin A, Iron and Calcium!! Also - brightly coloured vegetables have the added benifit of being PACKED with anti-oxidants! So she can chow down on salads with spinach, broccoli, brussel sprouts, purple cabbage, capsicum, tomato, beetroot, mushrooms, lettuce and other tasty things...
Legumes like chick-peas, lentils or beans are great for health - they help in maintaining blood pressure (can be a problem in pregnancy), provide extra fibre and protein, give low GI energy and have lots of vitamins and minerals. They are also good in that they offer her folate - which will help prevent spina-bifida. Low GI whole or rolled grains like oats, barley and rye are also great forms of low GI carbs... And these also help with blood pressure and cholesterol.
Fruits are also very beneficial. Things that are high in vitamins, phytochemicals and anti-oxidants like berries, oranges/citrus, apples, stone fruits.
Dairy products (with the exception of soft cheeses) are great. They are calcium-rich and offer her a good source of protein and carbs. Another food that might be a good idea would be eggs. Packed with protein, vitamins and minerals they are excellent! But watch her overall cholesterol intake - so she should limit the number of yolks.
Things that are high in omega-3 fats. So walnuts and flaxseeds are excellent. I would limit seafood sources like salmon (due to concerns with toxin accumulation) but nuts and seeds are great.
As for what to avoid, well, the usuals like alcohol and caffine are given... She should limit soft cheeses (listeria), seafood (mercury etc), cholesterol-rich foods (hard cheeses, yolks), artificial sweeteners (aspartame is ok in smaller amounts).
For exercise yoga and walking is great. As is swimming, bike riding and other forms of moderate cardio. She could probably do lighter weight training as well, especially in the earlier trimesters (if ok'd by her doctor). I know people who worked out in the weights room right up until 2 weeks before the birth, so it can be done...
Good luck and enjoy yourself!!