Hard to tell from the pic but I am seeing dead bees, and what looks like stores cappings or paper too, it's hard to make it out.
If your friend is worried enough to take a pic they should be worried enough to lift the lid and look. The balance here is do damage by doing nothing or do damage by looking, personally I would look. Oh and they should heft the hive too.
I agree, no mouse guard and the bee on the extreme left looks like it has a blob of something on its thorax. Possibly body fluids, which would suggest some sort of mechanical damage, i.e. teeth. Essential to ensure the mouse has gone and then do something about ensuring it doesn't return. A metal queen excluder (frameless) nailed across the entrance would work if they don't have a mouse guard to hand.
I think it was removed today to get a look at what was going on. we did not open them up because of the cold. they were a very small swarm that moved in of their own accord back in June. she has been feeding them syrup ever since. she does have some fondant but not sure if she has put that on yet, need to ask her. they did not expand that much over summer and they only filled a few frames with stores but we are hoping they are going to survive the winter.
she did put the mouse guard on late and i also did wonder if it was mouse damage. she has emailed the picture to the beeks that did the course for us in the summer but what with xmas we are not expecting a reply for a few days so that is why i thought it best to ask you lot. you have always been very helpful in the past.
is there anything you need to know to get a better idea of what is going on?
I check my landing boards daily, for curiosity, normally around mid-day. I was late today and one colony had many casualties on the landing board, several bees on the snow behind the hive and one or two still intent on making kamikasi flights. Snow still around.
I hope in your case that it's nothing serious either. Casualties and a bit of housekeeping perhaps? The temperature was up a degree or two today.