My wife is pregnant and her due date is on May. I am the only one employed.what is the process for applying the visit visa for my mother in law.

Your mother-in-law would apply  on form DS-160 and present at the time of interview the reason for which she wishes to visit the US, proof of her ties and bonds to the home country, and financial evidence that she will be able to stay in the country for the period of her visit without becoming a public charge. If you wish, you can support her application with your own letter explaining the temporary nature of the stay along with an I-134 affidavit of support (if needed or helpful) with job letter, banking statement and your last tax return. Due to the limitations of the Lawyers.com Forums, Alan Lee, Esq.'s (the "Firm") participation in responding to questions posted herein does not constitute legal advice, nor legal representation of the person or entity posting a question. No Attorney/Client relationship is or shall be construed to be created hereby. The information provided herein by the Firm is general, and requires that the poster obtain specific legal advice from an attorney. The poster shall not rely upon the information provided herein as legal advice nor as the basis for making any decisions of legal consequence.