Let $\mathbb{R}_c$ be $\mathbb{R}$ with the cocountable topology. We'll show that its cone is not locally path-connected, where the cone is $$X=(\mathbb{R}_c \times [0,1])/\sim$$ with $(x,t)\sim (x',t')$ if $t=t'=1$.
Lemma. Let $A$ be an uncountable set with the cocountable topology. Then compact subsets of $A$ are finite and connected subsets are either singletons or uncountable.
Proof. Suppose $B\subset A$ is compact and (countably or uncountably) infinite. Given any countably infinite subset $B_0\subset B$, we can cover $A$ with sets of the form $U_b=b \cup (A \setminus B_0)$ for $b \in B_0$. A finite subcollection of these sets $U_b$ can contain only finitely many elements of $B$, hence $B$ is not compact. Now suppose that $C \subset A$ is connected and contains more than one element. Since finite/countable subspaces in the cocountable topology have the discrete (subspace) topology, $C$ is uncountable. $\square$
Claim 1. Every path into $\mathbb{R}_c$ is constant. Thus no open subsets of $\mathbb{R}_c$ are path-connected; in particular, $\mathbb{R}_c$ is not locally path-connected.
Proof. Let $f:[0,1] \to \mathbb{R}_c$ be continuous. The image $f([0,1])$ is compact and connected, so it must be a singleton set by the lemma. $\square$
Claim 2. The cone on $\mathbb{R}_c$, denoted $X$, is not locally path-connected.
Proof. Fix a point $(x,t)$ in the open subset $\mathbb{R}_c \times [0,1) \subset X$. Any path $f:[0,1] \to\mathbb{R}_c \times [0,1)$ projects to a path $p \circ f:[0,1] \to \mathbb{R}_c$ under the projection $p: \mathbb{R}_c \times [0,1) \to \mathbb{R}_c$. By Claim 1, $p \circ f$ is constant, so all paths into $\mathbb{R}_c \times [0,1)$ have a fixed first coordinate. Because every open neighborhood of $(x,t)$ includes points $(x',t')$ with $x'\neq x$, it follows that no neighborhood of $(x,t)$ is path-connected. Thus $X$ is not locally path-connected. $\square$
Remark. Any uncountable set with the cocountable topology is connected because any two (nonempty) open sets intersect. It follows that open subsets of such a space are themselves uncountable sets with the cocountable (subspace) topology, hence all open subsets are connected. Then certainly the original space is locally connected. Since a finite product of locally connected spaces is locally connected, $\mathbb{R}_c \times [0,1]$ is locally connected. Quotient maps also preserve local connectedness, so this implies that the cone $X$ is locally connected.
The error is always near words like "surely" ;)
The set $A:=\{0\}\times (1-\epsilon,1]$ is not open in the comb space $C$. Indeed $((1/n, 1))_{n\in\mathbb N}$ is a sequence in $C\setminus A$ which converges to $(0,1)\in A$.
Best Answer
The comb space $C$ is not locally connected at all of its points. In fact, one can show that it is locally connected precisely at the points of $C \setminus \{0\}\times (0,1]$.
The claim here is that $D' = D \cup \{(0,1/n) \mid n \in \mathbb Z \}$ is locally connected at $(0,0)$ but not locally path connected at $(0,0)$. The second part is obvious: No neighborhood of $(0,0)$ in $D'$ is path connected because there does not exist a path from $(0,0)$ to any $(0,1/n)$. See also Deleted comb space is not path connected.
To see that $D'$ is locally connected at $(0,0)$, let $U$ be any neighborhood of $(0,0)$ in $D'$. Choose $r > 0$ such that $V = \left( [0,r) \times [0,r) \right) \cap D' \subset U$. Then $V$ is a connected open neighborhood of $(0,0)$. This comes from the fact that $W = \left( (0,r) \times [0,r) \right) \cap D' = \left( (0,r) \times [0,r) \right) \cap C$ is connected. Hence the closure $\overline{W}^C$ in $C$ is connected and since we have $W \subset V \subset \overline{W}^C$, also $V$ is connected.