I'd say she could do with a wake-up call to leave her cosy child-like dependency on you both and do something for herself. Fourteen years is a long time to give up responsibility for her own life while she recovered from her unsuccessful relationship and the results of it. In another five years her son could be studying in another town, and unless she makes other interests for herself she will be bereft.
It might take support (and persistence) to get her moved on, but when that succeeds you will all be able to live more independently and thus get on better together. Try not to make it full of criticism but as support for her to take back her life, but you may need to be firm in insisting that she take some kind of steps on her own behalf, painful though she may find them.
Is she getting treatment for the depression and social anxiety, and is she herself working at anything to improve it? Maybe she needs encouragement to pester return to the GP about it. She could ask for a referral to someone who will "retrain" her confidence and independence.
Does she volunteer at anything? That is an introduction to the routine of work, and will give her references for future employment. Does she have any hobbies which she could develop at an evening class or join a group that meets for a "knit and natter" type session ? That could provide chats and possible starts to friendships. Are there any lunch clubs or similar in your area?
Give her some specific responsibilities in the home. Tell her you are finding it quite tiring to do everything in the house, while she does almost nothing, and give her a choice of a couple of things from a short list that she could take on all the work of - maybe the bed-changing and laundry, or the shopping and checking that the staples in the store-cupboard are always topped up (you could keep a shopping-list on a notice-board that you added to yourself when you thought of things, if she is not good at knowing what is needed) or cooking meals a few times a week and clearing up afterwards.
As it is, you and she are in danger of falling out because you see too much of one another. You are feeling aggrieved because she is acting like a small child again, and she feels (and acts) like a small dependent child because she is not in charge of anything. That is not healthy for either of you.
You clearly think a lot of your grandschild, but at the end of the day, he is her child and she is his mother. There is a danger of him regarding you as that mother unless you can help your daughter grow up. That would not be good for any of you in the long run.