hem krish, my opinion is that the potting mix is the problem, too heavy, for indoor application. Moisture is held for too long in the top layer and is causing the leaves at the base to rot because they literally sit in water longer than is good for them. Further, I am willing to wager that deeper in the container, the mix is not allowed to dry out (air out is a better expression) and the roots therein are suffocating.

Thanks ronalawn82, that could be the answer!!! I am going to bring the plant home and mix in some sand to make the mix more porous and draining. Am I watering correctly? I water till the soil is drenched and water begins dripping out of the holes at the bottom. Should I water less now?

hem krish, I start off by saying that you will hardly kill a plant by overwatering it the first time. What will certainly do 'grievous bodily harm' is continuing to water it without caring how wet or dry the soil is. The soil is the water reservoir for the plant and the plant will take from the reservoir as needed. The water is held in the pore spaces but some of the same pore spaces must hold air, another necessity to the plant. It is this balance of air and water in the root zone of the container which determines the well being of the plant, ceteris paribus, IMHO and other similar qualifications.
But, to answer your question, try to determine how wet the soil is in the root area of the container. It should be black in color and barely hold together. Use a probe to capture some soil at various depths. If you can whittle, you can make a probe from a length of dowel rod. About half inch from the end, using a utility knife (or similar tool), make a crosscut half way into the dowel. Above this cut, start to whittle away the wood and work inward and upward until you achieve a gradual slanted surface ending in the middle of the dowel at the level of the crosscut. You should be left with a little niche so that if you push the dowel into the soil, rotate it half a turn and withdraw it, there should be a small soil sample sitting in the niche. Examine this for moisture content. Do the same for the soil near the bottom of the container. Is it more wet? soggy wet? If yes, then there might be no need for watering because water will move upward in the very tiniest of pores.
I guess that this has been quite a long winded way to say "it depends!" but I do trust you will find some useful information in all this.

Thank you for your detailed response ronalawn82. I had no idea that the root area of the plant mattered. I brought the plant home and pulled it out of the pot. Not surprisingly, though the top soil was dry, the soil was soggy and mushy where the roots were. I teased the roots apart and got out as much soil as I could. I added some sand and coco peat to the soil and repotted it. Now the plant seems to be doing fine and has new growth.

My spider plant that I have had for 12 years is turning black it's not holding any water do I need to transplant?