I agree with Pip , she needs a check-up at the vets if she has not had one lately.
Senior cats come with a slew of new conditions, just like we peeps. Incontinence is certainly one of them, and if she has gone blind, well that is a double whammy. Pip has a great idea with the puppy pads.
You can also move her litter box right next to her bed--maybe she will smell it and will not have far to go to find it.....or you can put her in a babies diaper bad pant with babies t-shirt over it to keep it tidy. The t shirt also will provide an additional layer of warmth. In the winter I put a heating pad under the cover of my seniors bed. She loves the extra warmth. You could try a hot water bottle under the covers, nothing electrical especially if she is going to be peeing on it, LOL!
Please try brushing her everyday ---she may be getting old and blind but she still needs to feel loved and beautiful. I am sure this is affecting her grooming habits, and that is depressing for kits. They are so used to preening and being their most beautiful.
Let us know what the vet says, let's just hope it is nothing more than her having some "Senior Moments"--you know the ones where we walk into a room all purposeful and then forget what we are there for. It is just as frustrating for her.
Keep us posted on our new addition Senior--we have many here to keep her company.
Good luck at the vets.
Hard to say, kitty may be losing control..seems a vet visit is in order.
Something you can do to help keep things cleaner, line her bed with puppy training pads. They are absorbent and will keep the bed dry in the meanwhile.