hypervascular lymph node on USG can be found in many diseases where lymph nodes ore affected, which may be benign (some reactive hyperplasias to malignant tumors).
so, in any case it needs evaluation, in fact a lymph node of this size in infant needs eveluation.
may be you get the answer from the FNAC report, but may be you have to go for BIOPSY
for confirmation if FNAC is inconclusive. in my opinion a complete blood count
with peripheral smear comment should also be done.
if there is no systemic illness other than this enlarged lymph node
the chances of any major illness is less, but can't be ruled out.
as far as second opinion
is concerned, you can ask for the slides of FNA / Biopsy from the pathlab and get it evaluated by a second pathologist. the final diagnosis will be done only by correlating the clinical findings and the report.
wish your daughter good health
Dr. Amit Kumar