Concept: Succession among Indian Christians is governed by the Indian Succession Act. The share of the spouse depends on whether the deceased left lineal descendants or kindred.
Step 1: Identify the facts.
The Christian lady dies leaving:
\[
\text{Husband + Mother + No child}
\]
So, there is no lineal descendant, but there is kindred because the mother is alive.
Step 2: Apply the rule of succession.
Where the deceased leaves no lineal descendant but leaves kindred, the surviving spouse takes one-half of the property.
\[
\text{No child + kindred present} \Rightarrow \text{Spouse gets } \frac{1}{2}
\]
Step 3: Choose the correct option.
Since the mother is alive, the husband does not take the whole property. He inherits half of the property.
Therefore, the correct answer is half of the property.