Hi Nitinkumar,
I went through your case and just my 2 cents, You may not required to have your mother beside you for your pregnancy delivery. Pls consultant your FP if you have any questions, they are more than happy to help you and explain you in detail each and every step from pre to post delivery. But having some one to assist you will greatly help.
As far as TRV is concerned, it has been refused twice so the probability of getting TRV is unlikely, you can still try but you need to be perfect the way you need to present the case to the Immigration officer.
When I looked @ your case, you mentioned that the purpose of your mother visit's is help you during your pregnancy delivery.Have you mentioned this in your invitation letter? If yes then its a big NO NO.. Immigration officer looks this in a different way.
Secondly , its better to avoid to transfer funds just for the TRV purpose,Immigration officer will figure it out.
Some of the questions to help you in this regard
1. Does your mother has a Bank Account, If yes since when ?
2. Does any of the property(Movable or Immovable) is in the name of your mother ? If yes what are they, you can also include FD,Land, house.
3. To be on safer side, you should look around to have $10,000 in your mother's account
4, Is your sibling is married with kids ?