Can I know what will be the best nourshing diet for a pregnant lady (from both mother baby perspective)

4 months have passed

Well, to start a pre-natal vitamin on a daily basis, basically a well balanced diet, plenty of fruits and veggies, meat, grains and lot's of dairy. It's pretty much what is recommended for the average adult to eat, just with some extra servings of dairy and veggies. Some women taken eating for two literally and eat double the food, which isn't good for them or the baby. Doctors usually recommend and extra 200-300 calories per day. However that also depends on the woman and what her health and weight were prior to the pregnancy.
Has she been seeing an OB/GYN regularly? That is something she should be doing, or at least a midwife or doula. Also, websites such as www.babycenter.com (http://www.babycenter.com) or www.whattoexpect.com (http://www.whattoexpect.com) are great resources full of all sorts of information and forums to talk with others going through similar highs and lows.
Good luck and all the best :D