When $10\text{ml}$ of $0.1\text{M}$ acetic acid ($p{K}_a=5.0$) is titrated against $10\text{ml}$ of $0.1\text{M}$ ammonia solution ($p{K}_b=5.0$), the equivalence point occurs at $pH$:

At the equivalence point, a salt of a weak acid (acetic acid) and a weak base (ammonia) is formed, which is ammonium acetate (${\text{CH}}_3{\text{COONH}}_4$). The $pH$ of a salt of a weak acid and a weak base is given by:
$$pH=7+\frac{1}{2}(p{K}_a-p{K}_b)$$
Given $p{K}_a=5.0$ and $p{K}_b=5.0$:
$$pH=7+\frac{1}{2}(5.0-5.0)=7.0$$