My mother recently had a squamous cell removed. should she also see an onc md?

It depends: Having a 'squamous cell' removed does not tell me enough. You probably a referring to a 'squamous cell carcinoma' of the skin. If so, the doctor removing it can tell you if the excision is complete. If complete, little more is needed except a good careful skin exam, good skin health (no tanning salons, please) + sunscreen and good followup.

No: I assume that it was squamous cell cancer (scc) of the skin. Scc is a very common skin cancer. Most of the time, surgical excision is all it takes. Unless there is a concern that it is an aggressive type and has travels to other parts of the body, there is no need to see an oncologist.

Possibly: Squamous cell of the skin can be very aggressive and spread to the lymph node and ultimately throughout the body if not treated. Usually if it is caught early and removed with clear margins then the patient is cured. If the cancer had aggressive features seen microscopically then sometimes the area may be treated with radiation by an oncologist. This depends on the cancer's stage though.