The asset is worth what it is worth, and if you inherit shares in the corporation or the land itself you will still receive stepped up basis in either asset. The fair market value of the asset as of date of death is your basis, and if the asset is stock in the corporation presumably it is worth what the land is worth.
If your mother dissolves the corporation and transfers the land back to herself it will very likely be a taxable event. Either a tax CPA or an Enrolled Agent can give you specific tax advice, but don't do anything until you consult one of the two.

