MapQuest Issue - Direct Tile Access No Longer Supported?
You can use OpenStreetMap tiles if you replace the tile pointer in this file:

.../templates/CRM/Contact/Form/Task/Map/OpenStreetMaps.tpl


Change this...

    map.addLayer(new OpenLayers.Layer.OSM("MapQuest OSM", [
        "https://otile1-s.mqcdn.com/tiles/1.0.0/map/${z}/${x}/${y}.jpg",
        "https://otile2-s.mqcdn.com/tiles/1.0.0/map/${z}/${x}/${y}.jpg",
        "https://otile3-s.mqcdn.com/tiles/1.0.0/map/${z}/${x}/${y}.jpg",
        "https://otile4-s.mqcdn.com/tiles/1.0.0/map/${z}/${x}/${y}.jpg",
    ], {
        attribution: "&lt;p&gt;Tiles Courtesy of &lt;a href='http://www.mapquest.com/' target='_blank'&gt;MapQuest&lt;/a&gt;. Data &amp;copy; &lt;a href='http://www.openstreetmap.org/' target='_blank'&gt;OpenStreetMap&lt;/a&gt; contributors.&lt;/p&gt;"
    })); 


To this ...

    map.addLayer(new OpenLayers.Layer.OSM("openstreetmap", [
        "https://a.tile.openstreetmap.org/${z}/${x}/${y}.png",
        "https://b.tile.openstreetmap.org/${z}/${x}/${y}.png",
        "https://c.tile.openstreetmap.org/${z}/${x}/${y}.png"
    ], {
        attribution: "&lt;p&gt;Map Courtesy of &lt;a href='http://www.openstreetmap.org/' target='_blank'&gt;OpenStreetMap&lt;/a&gt;&lt;/p&gt;"
    }));


You do want to use https!