This is a patch to fix all the 'free-without-setting to NULL' problems.
Some of these are addressed in later version of mongoose.

diff --git a/mongoose.c b/mongoose.c
index b92dec7..60d35ff 100644
--- a/mongoose.c
+++ b/mongoose.c
@@ -1173,6 +1173,7 @@ static int closedir(DIR *dir) {
       result = FindClose(dir->handle) ? 0 : -1;
 
     free(dir);
+    dir=NULL;
   } else {
     result = -1;
     SetLastError(ERROR_BAD_ARGUMENTS);
@@ -4279,6 +4280,7 @@ static void close_all_listening_sockets(struct mg_context *ctx) {
     closesocket(ctx->listening_sockets[i].sock);
   }
   free(ctx->listening_sockets);
+  ctx->listening_sockets = NULL;
 }
 
 // Valid listening port specification is: [ip_address:]port[s]
@@ -4653,6 +4655,7 @@ static void close_connection(struct mg_connection *conn) {
   // Must be done AFTER socket is closed
   if (conn->ssl != NULL) {
     SSL_free(conn->ssl);
+    conn->ssl = NULL;
   }
 #endif
 }
@@ -4661,10 +4664,12 @@ void mg_close_connection(struct mg_connection *conn) {
 #ifndef NO_SSL
   if (conn->client_ssl_ctx != NULL) {
     SSL_CTX_free((SSL_CTX *) conn->client_ssl_ctx);
+    conn->client_ssl_ctx = NULL;
   }
 #endif
   close_connection(conn);
   free(conn);
+  conn = NULL;
 }
 
 struct mg_connection *mg_connect(const char *host, int port, int use_ssl,
@@ -4815,6 +4820,7 @@ static void process_new_connection(struct mg_connection *conn) {
     }
     if (ri->remote_user != NULL) {
       free((void *) ri->remote_user);
+      ri->remote_user = NULL;
     }
 
     // NOTE(lsm): order is important here. should_keep_alive() call
@@ -4907,6 +4913,7 @@ static void *worker_thread(void *thread_func_param) {
       close_connection(conn);
     }
     free(conn);
+    conn = NULL;
   }
 
   // Signal master that we're done with connection and exiting
@@ -5061,6 +5068,7 @@ static void free_context(struct mg_context *ctx) {
   // Deallocate SSL context
   if (ctx->ssl_ctx != NULL) {
     SSL_CTX_free(ctx->ssl_ctx);
+    ctx->ssl_ctx = NULL;
   }
   if (ssl_mutexes != NULL) {
     free(ssl_mutexes);
@@ -5070,6 +5078,7 @@ static void free_context(struct mg_context *ctx) {
 
   // Deallocate context itself
   free(ctx);
+  ctx = NULL;
 }
 
 void mg_stop(struct mg_context *ctx) {