Our cat (female) 16 years old has lost her long term cat companion (brother 6 month younger) last year. I had the veterinarian coming to the house to put him down as I wanted him to die in his home.
The two cats lived together for all their lives. He came 6 months later and at first it caused a week of trouble but soon my female cat got used to him.
My male cat was a very confident cat outside and happy with people around whereas the female cat is very shy and scared of her own shadow. Her favourite place is the bed.
Just before the veterinarian came, my female cat came downstairs and as if she sensed danger coming, she went outside and cried towards the car park. She was upstairs though when the veterinarian put her cat brother to sleep.
She would not come down for 3 months and was also stressed by other events (e.g.: removal boxes in the house, a mouse in the kitchen (we live in an old farm house) which caused her not to set a paw into the kitchen - I know, a cat!!!)
She even started to wee just outside her litter tray and onto our duvets. We managed to make the connection and got rid of the boxes and the mouse. After that, our kitty came downstairs again for some time and played with us.
Outside was another matter as the female cat had always relied on the male cat for confidence; she would just follow him into the garden and go wherever he would go.
Now our female cat has taken to spending most of her time in bed again, only leaving the bed for food, toilet, to use her scratch board (also in bedroom) and to play with us. There are also toys downstairs in the living room which she used to use before.
We give her aktivait as she seemed confused and at a loss for some time.
Every time somebody stays with us for a visit or she does not like something, our cat has taken to wee onto our duvets again, otherwise she does it into the litter tray.
I don't know what is best for her. I would not mind to take another old female cat on from a cattery to give her a new home and also to give Mischka a new companion (maybe it would make her better again). But she always was a very territorial cat, I saw her chasing a kitten off which came too close to the house before. I don't want to stress her (or the new cat) further, either.
What would be the best, how can I help our cat, Mischka ? We are both out all day at work and she is all alone which she only spends in bed and when we come home and go to bed she sleeps with us in bed all night too.
I am sorry for your loss. It is difficult when we lose our beloved kitties, both for us and for their cat friends.
There is not one definite answer to your question. Every cat is different and will react differently to losing a friend and to acquiring a new one.
It certainly sounds as if your female cat really has mourned the loss of her "brother" cat. By now, however, she should be (and it sounds as if she is) accustomed to the different life and is likely over any mourning stage.
Many cats that have lived with another cat for many years and then lose their cat friend go on to be very happy and contented being the only cat. Yes, you are out of the house all day, and Mischka is alone, but sleeping is the main activity of cats her age anyway.
As an example, I have the pleasure of working from home today and as I write this, all my cats are sleeping in various places throughout the house and have no interest in me whatsoever!
Older cats in general are more stressed by the addition of a new cat into the household than are younger cats. As you know, cats in general take some time adjusting to new cats and it doesn't always work out.
You know your cat, Mischka, and I don't, of course, and you can better assess her personality and mood and whether you think she longs for a companion.
I would caution you, however, to consider that there is no other cat in the world that you could bring in now that would take the place of her former cat friend and she will never have another relationship with another cat in the same way she did with him.
I would also strongly advise you that if you decide to get another cat, an older female would not be wise. An older cat in general would not be wise. Mischka will have a much harder time adjusting to an adult cat than she would a kitten or young cat.
I would also encourage you to try (and this is hard to do) to look through your cat's eyes and not human eyes as you assess the situation. The way we see things may not be the way she feels at all. We may think she is lonely; she may be perfectly content. Again, it is difficult to put our human feelings aside, but you can try.
I'm sorry I can't tell you what to do, but I hope I have given you some food for thought.
I will also add as I'm finishing my answer that as I look around at my napping cats today, not only are they napping and ignoring me, but they are each sleeping alone in their own individual places. And they are great friends and coexist happily together, but they are very content to sleep the day away in their own little space.
Best wishes to you and your kitty, Mischka