beverley, I'm not surprised you are feeling confused by the ever-changing information you are being given by the professionals involved in your case. They don't seem to be working together and they certainly don't seem to be involving you in their thought processes.
Firstly, the guardian and social worker have no business being concerned that if you have the baby, this will leave your daughter without support. They should be very clear that, to put it bluntly, their priority is the baby and not your daughter. If the best place for the baby is in your care, then quite frankly your daughter's welfare is irrelevant to them. If they are truly concerned that your daughter may be vulnerable then they should be making appropriate referrals elsewhere on her behalf.
Secondly, it comes across very clearly from your posts that your priority is the baby and not your daughter. You said earlier that their only concern to arise from the assessment was whether you would feel able to put the baby's needs above those of your daughter (sorry but I can't remember your exact words). I can't understand why they seem to be finding it so difficult to accept this. Have you put anything in writing at all? I just wonder whether you have considered writing to the Director of Children's Services expressing your total commitment to your grandchild. You could also (if you felt it appropriate) say that some concerns have been shared with you but you have not yet had the opportunity to see a copy of your assessment report, so you are not clear about the exact concerns.
I think you are doing everything possible at the moment and I do hope it all works out for you. Keep fighting.