[рони]

milov,

var myCollection = new ymaps.GeoObjectCollection({});
data.item.forEach(function(el, i) {
    var layout = ymaps.templateLayoutFactory.createClass('<div><img src="..."/></div>');
    var layout_hover = ymaps.templateLayoutFactory.createClass('<div><img src="..."/></div>');
    var myPlacemark = new ymaps.Placemark([lat, lng], {...}, {
                    iconLayout: layout,
                    iconShape: {
                        type: 'Circle',
                        coordinates: [0, 0],
                        radius: 25
                    }
                });

    myPlacemark.events
        .add('mouseenter', function (e) {
            e.get('target').options.set("iconLayout", layout_hover);
        })
        .add('mouseleave', function (e) {
            e.get('target').options.set("iconLayout", layout);
        });

    myCollection.add(myPlacemark);
})
myMap.geoObjects.add(myCollection);