Transfer visit visa to dependent visa

My wife in visit visa now and its will completing on 13th July 2018 (3 month will complete).

Our group of companies has 2 company (2 sponsor), my employer applied my wife visit visa using our 1st sponsor (where i worked before), now they are changed my work visa to 2rd sponsor (today its got approved). Now they are going to apply for dependent visa for my wife using my 2rd sponsor.

Now how many days it will take for the transfer of visa from visit visa to my dependent visa  (now she is in Bahrain with our old sponsor visit visa).

And Also she is pregnant now doctor given certificate not to travel 3 month (which is completing  on 15th Aug'2018). If my company are not able to get the visa done before 13th July 2018, will i can directly go and request for visa extension ? (for this special case).

You have to file application for transfer at least 7 days before expiry of the visit visa.  Once it is in process, you don't have to worry, no matter how long it takes.

today my new sponsor, my visa changed to to new sponsor (but i did not did finger print and new CPR procedure also). Today they given 1 month notice to me now.

my wife visa is still in my old sponsor and its expiring on 13th july 18.

whether me and my wife can stay additional 1 more month. (my employer will cancel my visa this month end)

Please tell me solution. I stacked now

I have no idea what you are saying.

Do you have a work visa stamped on your passport or not?   if not, has it been applied for?  If you have a work visa application in process or approved; there is nothing to worry about.  You can stay.

For your wife visit visa, I have already made the comment above.   Apply for her dependent visa 7 days before expiry of visit visa and you can stay.  Otherwise she will need to exit and apply from abroad.