Step 1: Find the equation of the line joining the given points.
The given points are
\[
(0,3)
\]
and
\[
(5,-2)
\]
Slope of the line is
\[
m=\frac{-2-3}{5-0}
\]
\[
m=\frac{-5}{5}=-1
\]
Using point-slope form through \((0,3)\),
\[
y-3=-1(x-0)
\]
\[
y=-x+3
\]
Step 2: Use the tangency condition.
The curve is
\[
y=\frac{C}{x+1}
\]
At the point of tangency, the line and the curve intersect at exactly one point.
So,
\[
\frac{C}{x+1}=-x+3
\]
Multiplying by \((x+1)\),
\[
C=(-x+3)(x+1)
\]
Expand:
\[
C=-x^2+2x+3
\]
Rearranging,
\[
x^2-2x+(C-3)=0
\]
Since the line is tangent to the curve, this quadratic must have equal roots.
Therefore,
\[
D=0
\]
Step 3: Apply discriminant condition.
For
\[
x^2-2x+(C-3)=0,
\]
the discriminant is
\[
(-2)^2-4(1)(C-3)=0
\]
\[
4-4C+12=0
\]
\[
16-4C=0
\]
\[
4C=16
\]
\[
C=4
\]
Step 4: Final conclusion.
Therefore,
\[
\boxed{4}
\]