Can I apply fusidic acid cream on the scalp where newly hair grafts are placed?

You should ask your doctor this question as each doctor has different post operative care instructions.  Some doctors a very specific.  The another issue is WHY?  Why would you want to do this and where did you get the idea?

Check with your surgeon for his or her protocol for post op care. Fusidic acid is not usually needed for the grafts - unless there is an infection. Some surgeons recommend these antibiotic creams for the donor area - but many surgeons do not. All is all, check with your surgeon

First I don't know why you would use this as this fusidic is an irritant and could damage your scalp skin. Check with your doctor first before you do this.