Are these 3 molecular structures of ammonium bicarbonate the same?
Like Punarbasu Roy already stated, the depicted structures are certainly not the same. To be frank, only one of them (A) is correct, one of them is not completely wrong (B - but only because it is incomplete), and one is completely, utterly wrong (C).

In lieu of an actual crystal structure of ammonium hydrogencarbonate,[1] I'll refer to the structure of the parent compound ammonium carbonate monohydrate to make my point.[2] It is actually quite difficult to assign one correct Lewis structure. In its solid form ammonium (bi)carbonate is a salt, in which ammonium and (bi)carbonate ions are interacting via ionic bonds in a lattice. In solution this certainly is broken up and we will find separate ions, according to the following equilibria:
\begin{align}
\ce{(H4N)HCO3~(s) &amp;~-&gt;C[(H2O)] NH4+ ~(aq) + HCO3- ~(aq)}\\
\ce{NH4+ ~(aq) + H2O &amp;~&lt;=&gt; H3+O~(aq) + NH3~(aq)}\\
\ce{HCO3- ~(aq) + H2O &amp;~&lt;=&gt; H2CO3 ~(aq) + {}^{-}OH~(aq)}\\
\ce{HCO3- ~(aq) + H2O &amp;~&lt;=&gt; CO3^2- ~(aq) + H3+O~(aq)}\\
\end{align}
The same equilibria will establish for ammonium carbonate with different concentrations.

In the crystal structure of ammonium carbonate monohydrate you can see the different molecular entities (ions) held together via hydrogen bonds, reproduced from [2]:
  

Wikipedia[3] therefore offers the best possible Lewis structure:




Strictly speaking a Lewis structure may only contain covalent bonds, i.e. two-centre-two-electron bonds, while ionic bonds are implied by placing the (molecular) ions in close proximity to each other. However, the hydrogen bond is a well known concept in chemistry and it was already extensively discussed by Linus Pauling. In his book "The Nature of the Chemical Bond" he uses dashed lines to represent the hydrogen bond.[4] Certainly another interesting read is the approach of a more unified theory about the hydrogen bond.[5]
Another possibility is to introduce the donor-acceptor notation with arrows, to indicate a bonding interaction. Therefore one of the following structures may also be considered correct in an extended Lewis concept.






The following article reads like this is still a work in progress: R. Brooks, and T. C. Alcock, Nature, 1950, 166, 435-436. (It does also not come with any supporting information.
A. D. Fortes, I. G. Wood, D. Alfè, E. R. Hernández, M. J. Gutmann, and H. A. Sparkes, Acta Cryst. Sec. B, 2014, 70, 948-962. This quite interesting article is open access.
Ammonium bicarbonate, Ammonium carbonate
Linus Pauling: The Nature of the Chemical Bond. Cornell University Press, 1960.
G. Gilli, P. Gilli, J. Mol. Struc., 2000, 552 (1-3), 1-15.